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Suppose that you have an abstract for a scientific paper: this paper describes a methodology ( or treatment ) to establish a representative signal of the global magnetic diurnal variation based on a spatial distribution in both longitude and latitude of a set of magnetic stations as well as their magnetic behavior on a time basis . for that , we apply the principal component analysis ( pca ) technique implemented using gapped wavelet transform and wavelet correlation . the continuous gapped wavelet and the wavelet correlation techniques were used to describe the features of the magnetic variations at vassouras ( brazil ) and other @xmath0 magnetic stations spread around the terrestrial globe . the aim of this paper is to reconstruct the original geomagnetic data series of the h - component taking into account only the diurnal variations with periods of @xmath1 hours on geomagnetically quiet days . with the developed work , we advance a proposal to reconstruct the baseline for the quiet day variations ( sq ) from the pca using the correlation wavelet method to determine the global variation of pca first mode . the results showed that this goal was reached and encourage other uses of this approach to different kinds of analysis . magnetogram data , h - component , quiet days , principal component wavelet analysis . . And you have already written the first three sentences of the full article: a substantial part of the energy carried by the solar wind can be transfered into the terrestrial magnetosphere and it is associated with the passage of southward directed interplanetary magnetic fields , bs , by the earth for sufficiently long intervals of time . discussed the energy transfer process as a conversion of the directed mechanical energy from the solar wind into magnetic energy stored in the magnetotail of earth s magnetosphere and its reconversion into thermal mechanical energy in the plasma sheet , auroral particles , ring current , and joule heating of the ionosphere . the increase on the solar wind pressure is responsible for the energy injections and induces global effects in the magnetosphere called geomagnetic storms . the characteristic signature of geomagnetic storms can be described as a depression on the horizontal component of the earth s magnetic field measured at low and middle latitude ground stations .. Please generate the next two sentences of the article

the decrease in the magnetic horizontal field component is due to an enhancement of the trapped magnetospheric particle population , consequently an enhanced ring of current . this perturbation of the h - component could last from several hours to several days ( as described by * ? ? ?

Suppose that you have an abstract for a scientific paper: we present molecular dynamics simulations of solid nano@xmath0 using pair potentials with the rigid - ion model . the crystal potential surface is calculated by using an _ a priori _ method which integrates the _ ab initio _ calculations with the gordon - kim electron gas theory . this approach is carefully examined by using different population analysis methods and comparing the intermolecular interactions resulting from this approach with those from the _ ab initio _ hartree - fock calculations . our numerics shows that the ferroelectric - paraelectric phase transition in solid nano@xmath0 is triggered by rotation of the nitrite ions around the crystallographical @xmath1 axis , in agreement with recent x - ray experiments [ gohda _ et al . _ , phys . rev.b * 63 * , 14101 ( 2000 ) ] . the crystal - field effects on the nitrite ion are also addressed . remarkable internal charge - transfer effect is found . . And you have already written the first three sentences of the full article: sodium nitrite is a ferroelectric at room temperature . it has the orthorhombic structure , space group @xmath2 , with the dipole vector of the v - shaped nitrite anions aligned parallel to the crystallographic @xmath3 direction , as shown in fig . [ fig : nano2 ] . crystal structure of nano@xmath0 in the ferroelectric phase . ] the ferroelectric - paraelectric phase transition takes place at about @xmath4 k , where the high temperature phase is orthorhombic , space group @xmath5 , with the dipoles disordered with respect to the @xmath3 axis . in a narrow temperature range from @xmath6 k to @xmath4 k. Please generate the next two sentences of the article

, there exists an incommensurate antiferroelectric phase . the melting temperature is @xmath7 k. distinguished from displacive ferroelectrics in which the ferroelectric transition is driven by soft phonon modes , nano@xmath0 offers a model system for research of the order - disorder structural phase transition and any associated ferroelectric instability .

Suppose that you have an abstract for a scientific paper: in this paper we develop a polymer expansion with large / small field conditions for the mean resolvent of a weakly disordered system . then we show that we can apply our result to a two - dimensional model , for energies outside the unperturbed spectrum or in the free spectrum provided the potential has an infra - red cut - off . this leads to an asymptotic expansion for the density of states . we believe this is an important first step towards a rigorous analysis of the density of states in the free spectrum of a random schrdinger operator at weak disorder . = -0.54 truecm = -0.54 truecm = 0 truecm = 0 truecm = 0 truecm = 0 truecm = 23 truecm = 17 truecm amssym.def amssym.tex . And you have already written the first three sentences of the full article: in the one - body approximation , the study of disordered systems amounts to the study of random schrdinger operators of the form @xmath0 where @xmath1 is a kinetic term ( _ i.e. _ a self - adjoint or essentially self - adjoint operator corresponding to some dispersion relation , typically a regularized version of @xmath2 ) and @xmath3 is a real random potential ( in the simplest case , @xmath3 is a white noise ) . we work on a ultra - violet regular subspace of @xmath4 and we restrict ourselves to @xmath5 small so as to see @xmath6 as a kind of perturbation of the free hamiltonian . the properties of @xmath7 are usually established through the behavior of the kernel of the resolvent operator or green s function ( @xcite , @xcite , @xcite ) @xmath8 for instance , the density of states is given by @xmath9 the important point is that , in the thermodynamic limit , the system is self - averaging , _ i.e. _ mean properties are often almost sure ones .. Please generate the next two sentences of the article

thus the problem can be seen as a statistical field theory with respect to the random field @xmath3 . in statistical mechanics , functional integrals in the weakly coupled regime are controled through a cluster expansion ( or polymer expansion ) with small field versus large field conditions , the problem being then to control a boltzmann weight ( @xcite , @xcite ) . in the first part of this paper ,

Suppose that you have an abstract for a scientific paper: networks of contacts capable of spreading infectious diseases are often observed to be highly heterogeneous , with the majority of individuals having fewer contacts than the mean , and a significant minority having relatively very many contacts . we derive a two - dimensional diffusion model for the full temporal behavior of the stochastic susceptible - infectious - recovered ( sir ) model on such a network , by making use of a time - scale separation in the deterministic limit of the dynamics . this low - dimensional process is an accurate approximation to the full model in the limit of large populations , even for cases when the time - scale separation is not too pronounced , provided the maximum degree is not of the order of the population size . . And you have already written the first three sentences of the full article: mathematical models are used throughout infectious disease epidemiology to understand the dynamical processes that shape patterns of disease @xcite . while early models did not include complex population structure , modeling approaches now frequently let the epidemic spread take place on a network , which enables greater realism than a model in which all individuals mix homogeneously . it does , however , pose many technical problems for model analysis , particularly the question of how heterogeneity in the number of links each individual participates in their degree influences the epidemic @xcite . similarly , even though some of the earliest mathematical models of infectious diseases were stochastic , accounting for the chance nature of transmission of infection @xcite , much of the applied modeling that followed was deterministic and based on non - linear differential equations @xcite . more recent applied work has , however , recognized the importance of using stochastic epidemic models @xcite and also of the development of associated methodology @xcite .. Please generate the next two sentences of the article

the difficulty in mathematically analyzing models which include both stochastic elements and network structure can be a reason for not including these factors , but we prefer to include them , and subsequently to systematically reduce the complexity of the resulting model . this is the approach we adopt in this paper ; the reduction process being made possible because of the existence of a separation of time - scales : many variables `` decaying '' away rapidly , leaving a few slow variables which govern the medium- to long - term dynamics . compartmental models of epidemics typically assume that the majority of the population starts susceptible to infection , with a small number infectious , who then spread infection to others before recovering .

Suppose that you have an abstract for a scientific paper: observation of the @xmath0 in the @xmath1 invariant mass in @xmath2 at besiii is reviewed . with a sample of @xmath3 @xmath4 events collected with the besiii detector at bepcii , the @xmath0 is observed with a statistical significance of @xmath5 . the mass , width and product branching fraction of the @xmath0 are determined . the decay @xmath6 is searched for , and the upper limit of the branching fraction is set at the 90% confidence level . observation of the @xmath0 at besiii . And you have already written the first three sentences of the full article: within the standard model framework , the strong interaction is described by quantum chromodynamics ( qcd ) , which suggests the existence of the unconventional hadrons , such as glueballs , hybrid states and multiquark states . the establishment of such states remains one of the main interests in experimental particle physics . decays of the @xmath4 particle are ideal for the study of the hadron spectroscopy and the searching for the unconventional hadrons . in the decays of the @xmath4 particle ,. Please generate the next two sentences of the article

several observations in the mass region 1.8 gev / c@xmath7 - 1.9 gev / c@xmath7 have been presented in different experiments@xcite@xcite , such as the @xmath8@xcite@xcite , @xmath9@xcite@xmath10@xcite , @xmath11@xcite@xmath10@xcite and @xmath12@xcite . recently , using a sample of @xmath13 @xmath4 events@xcite collected with besiii detector@xcite at bepcii@xcite , the decay of @xmath2 was analyzed@xcite , and the @xmath0 was observed in the @xmath1 mass spectrum with a statistical significance of @xmath5 . .

Suppose that you have an abstract for a scientific paper: follow - up observations of large numbers of gamma - ray burst ( grb ) afterglows , facilitated by the swift satellite , have produced a large sample of spectral energy distributions and light curves , from which the basic micro- and macrophysical parameters of afterglows may be derived . however , a number of phenomena have been observed that defy explanation by simple versions of the standard fireball model , leading to a variety of new models . polarimetry has shown great promise as a diagnosis of afterglow physics , probing the magnetic field properties of the afterglow and geometrical effects ( e.g. jet breaks ) . unfortunately , high quality polarimetry of a significant sample of afterglows is difficult to acquire , requiring specialised instrumentation and observing modes . in this talk i will review the recent successes in afterglow polarimetry , also showing first results of new instruments and observing campaigns . i will particularly focus on jet breaks . . And you have already written the first three sentences of the full article: right after the first detection of optical afterglows of gamma - ray bursts ( grbs ) and the diagnosis of grb afterglow radiation as synchrotron emission , predictions have been made for the linear and circular polarisation of grbs and their afterglows ( see for a review lazzati 2006 and references therein ) . while time resolved polarimetry of sources as faint and transient as grb afterglows is technically complicated and requires specialised instrumentation on large telescopes , the rewards are high : from time resolved polarimetric light curves we can determine grb parameters ( e.g. the jet structure , magnetic field configuration , viewing angle , etc . ) that can not easily be measured from light curves alone . the first detections of polarisation of afterglows in the pre - swift era demonstrated technical feasibility , and shown that afterglows generally have low levels of polarisation ( @xmath0 ) that vary as a function of time ( see lazzati 2006 for an overview of pre - swift measurements ) .. Please generate the next two sentences of the article

the swift era has provided further incentive to perform detailed polarimetry : the observed richness in afterglow light curve morphology ( x - ray flares , plateaux , steep decays etc . , see evans 2009 for statistics ) , has resulted in new models with various additional components to the standard fireball model , including for example the effects of high latitude emission , variable microphysics , energy injection mechanisms , etc .

Suppose that you have an abstract for a scientific paper: galactic cosmic ray ( cr ) acceleration to the knee in the spectrum at a few pev is only possible if the magnetic field ahead of a supernova remnant ( snr ) shock is strongly amplified by cr escaping the snr . a model formulated in terms of the electric charge carried by escaping cr predicts the maximum cr energy and the energy spectrum of cr released into the surrounding medium . we find that historical snr such as cas a , tycho and kepler may be expanding too slowly to accelerate cr to the knee at the present time . [ firstpage ] cosmic rays , acceleration of particles , shock waves , magnetic field , ism : supernova remnants . And you have already written the first three sentences of the full article: during diffusive shock acceleration ( dsa ) cosmic rays ( cr ) gain energy by repeatedly passing back and forth between the upstream and downstream plasmas ( krymskii 1977 , axford et al 1977 , bell 1978 , blandford & ostriker 1978 ) . cr diffuse ahead of the shock to form a precursor with an exponential scaleheight @xmath0 where @xmath1 is the shock velocity and @xmath2 is the cr diffusion coefficient upstream of the shock . the average dwell - time spent upstream of the shock between successive shock crossings is @xmath3 for relativistic particles ( bell 2012 ) .. Please generate the next two sentences of the article

this , along with the corresponding downstream dwell - time , determines the rate at which cr are accelerated . lagage & cesarsky ( 1983a , b ) showed that the time taken for cr acceleration is @xmath4 where @xmath5 is the downstream diffusion coefficient and @xmath6 is the downstream fluid velocity in the shock rest frame . since @xmath7 for a strong shock it might appear that the downstream dwell - time determines the acceleration rate , but we can expect @xmath8 partly because the magnetic field is increased by compression by the shock , partly because the compressed downstream magnetic field is more closely perpendicular to the shock normal , and partly because the downstream field is disturbed and more irregular after passing through the shock .

Suppose that you have an abstract for a scientific paper: after a review of exotic statistics for point particles in 3d @xmath0 theory , and especially 3d quantum gravity , we show that string - like defects in 4d @xmath0 theory obey exotic statistics governed by the ` loop braid group ' . this group has a set of generators that switch two strings just as one would normally switch point particles , but also a set of generators that switch two strings by passing one through the other . the first set generates a copy of the symmetric group , while the second generates a copy of the braid group . thanks to recent work of xiao - song lin , we can give a presentation of the whole loop braid group , which turns out to be isomorphic to the ` braid permutation group ' of fenn , rimnyi and rourke . in the context 4d @xmath0 theory this group naturally acts on the moduli space of flat @xmath1-bundles on the complement of a collection of unlinked unknotted circles in @xmath2 . when @xmath1 is unimodular , this gives a unitary representation of the loop braid group . we also discuss ` quandle field theory ' , in which the gauge group @xmath1 is replaced by a quandle . . And you have already written the first three sentences of the full article: physically speaking , the goal of this paper is to study the exotic statistics of loop - like defects in a 4-dimensional topological field theory called @xmath0 theory . we call these entities ` closed strings ' for short , though they behave differently from the closed strings familiar in string theory : the relevant lagrangian is different . in fact , we postpone the study of their dynamics to another paper @xcite .. Please generate the next two sentences of the article

the considerations of this paper are purely topological , and accessible we hope to mathematicians with only a passing interest in physics . mathematically speaking , the point of this paper is to study some representations of a higher - dimensional analogue of the braid group : the ` loop braid group ' .

Suppose that you have an abstract for a scientific paper: we report the discovery of hat - p-16b , a transiting extrasolar planet orbiting the @xmath0 f8 dwarf gsc 2792 - 01700 , with a period @xmath1 , transit epoch @xmath2 ( bjd ) , and transit duration @xmath3d . the host star has a mass of @xmath4@xmath5 , radius of @xmath6@xmath7 , effective temperature k , and metallicity @xmath8}}= { \ifthenelse{\equal{{ii}}{i}}{{\ensuremath{0.15\pm0.06}}}{{\ensuremath{+0.17\pm0.08}}}}$ ] . the planetary companion has a mass of @xmath9@xmath10 , and radius of @xmath11@xmath12 yielding a mean density of @xmath13@xmath14 . comparing these observed characteristics with recent theoretical models , we find that hat - p-16b is consistent with a 1 gyr h / he - dominated gas giant planet . hat - p-16b resides in a sparsely populated region of the mass radius diagram and has a non - zero eccentricity of @xmath15 with a significance of @xmath16 . . And you have already written the first three sentences of the full article: planets that transit their host stars play a special role in our understanding of the characteristics of exoplanets : their transit allows us to accurately determine the radius and the orbital inclination of the planet from the photometric light curve so that an actual mass can be derived from a spectroscopic orbit of the host star . the mass and radius enable us to infer a bulk composition of the planet , and although there are degeneracies associated with the bulk composition , it allows us to put constraints on models of planetary structure and formation theories . the incredible diversity of the over 60 discovered transiting planets , ranging from dense planets with a higher mean density than that of copper to strongly irradiated puffed - up planets with a mean density comparable to that of corkwood , have baffled the exoplanet community , and no unified theory has been established to explain all the systems consistently . transiting extrasolar planet ( tep ) discoveries are primarily the result of dedicated ground based searches , such as superwasp @xcite , hatnet @xcite , tres @xcite and xo @xcite , and space - borne searches , such as corot @xcite and kepler @xcite .. Please generate the next two sentences of the article

since its commissioning in 2003 , the hungarian - made automated telescope network ( hatnet ; * ? ? ? * ) survey has been one of the major contributors to the discoveries of teps .

Suppose that you have an abstract for a scientific paper: we report the structural and electron transport properties of rnbs2 ( @xmath0 ) and 3r-2 ( @xmath1 ) prepared as polycrystalline pellets as well as single crystals grown by vapour transport . we observe a resistance minimum in these compounds between 2060 k , with the proportional to @xmath2 . the resistance scales as @xmath3 between @xmath4 for different phases with @xmath5 whose resistivity differs by an order of magnitude . powder x - ray diffraction ( xrd ) also shows progressively increasing intensity of superlattice lines with cation concentration . the thermopower changes sign around the resistance minimum . the explanation of the resistance minimum and the simultaneous rapid suppression of superconductivity is sought in @xmath6-@xmath6 scattering effects in the presence of cation disorder in these narrow band anisotropic materials . 2nbs@xmath7 hnbs22h - nbs@xmath7 rnbs23r - nb@xmath8s@xmath7 2ga@xmath9nbs@xmath7 * pacs numbers : * + 72.80.ga transition metal compounds . + 71.45.lr charge density wave systems . + 74.62.bf effects of material synthesis , crystal structure , and chemical composition . + * running head : * low temperature resistance minimum , . And you have already written the first three sentences of the full article: the layered transition metal dichalcogenides ( ltmds ) mx@xmath7 of the group v metals ( m = v , nb , ta ; x = s , se ) and their intercalation compounds have been the subject of numerous studies on the inter - relationship between superconductivity and charge density waves ( cdw ) , both of which arise from the strong electron - phonon ( @xmath6-@xmath10 ) coupling within the layers @xcite . parameters such as stoichiometry , polymorphism , disorder and intercalation have been extensively used to study the physical properties of these low dimensional compounds . there is however , no satisfactory explanation for their effect on the above transitions . amongst the binary compounds , all di - selenides ( v , nb , ta ) and all polymorphs of tas@xmath7 show cdw transitions , while the 2h and 4h nb and ta compounds are also superconducting .. Please generate the next two sentences of the article

hnbs2 and 1t - vs@xmath7 are unusual in the former , any cdw is suppressed below the superconducting @xmath11 6.2 k due to @xmath6-@xmath6 interactions in the narrow unhybridised nb @xmath12 bands . 1t - vs@xmath7 is structurally metastable , supposedly due to reduced covalency which destabilizes the layered structure in its stoichiometric composition .

Suppose that you have an abstract for a scientific paper: we discuss two different models for the impact parameter dependent dipole cross section : one based on dglap evolution and the other inspired by the balitsky kovchegov equation . the parameters are determined from fits to data on the total @xmath0 cross section measured at hera . the impact parameter dependent saturation scale is extracted . predictions are then confronted with hera data on exclusive diffractive vector meson production and deeply virtual compton scattering . finally , predictions are given for the cross sections of exclusive photoproduced @xmath1 and @xmath2 mesons , and @xmath3 bosons , expected at the tevatron and lhc . . And you have already written the first three sentences of the full article: the colour dipole model has proven to be very successful in describing a wide variety of small-@xmath4 inclusive and diffractive processes at hera . this talk @xcite is based on work done on this subject in collaboration with h. kowalski and l. motyka @xcite . r0.5 [ fig : diagram ] the amplitude for an exclusive diffractive process , @xmath5 , shown in fig .. Please generate the next two sentences of the article

[ fig : diagram ] , such as vector meson production , @xmath6 , or deeply virtual compton scattering ( dvcs ) , @xmath7 , can be expressed as @xmath8\cdot\boldsymbol{\delta}}\;\frac{\mathrm{d}\sigma_{q\bar q}}{\mathrm{d}^2\boldsymbol{b}},\end{gathered}\ ] ] up to corrections from the real part of the amplitude and from skewedness ( @xmath9 ) . here , @xmath10 is the fraction of the photon s light - cone momentum carried by the quark , @xmath11 is the transverse size of the @xmath12 dipole , while @xmath13 is the impact parameter , that is , @xmath14 is the transverse distance from the centre of the proton to the centre - of - mass of the @xmath12 dipole ; see fig .

Suppose that you have an abstract for a scientific paper: among the different types of sources shining in the high energy sky , gamma - ray binaries are rapidly becoming the subject of major interest . in fact , in the last few years a number of high mass x - ray binaries ( hmxbs ) have been firmly detected from mev to tev energies , providing secure evidences that particles can be efficiently accelerated up to very high energies in such galactic systems . similarly to this general and emerging class of gamma - ray binaries , in principle supergiant fast x - ray transients ( sfxts ) have all the `` ingredients '' to be transient high energy emitters . in this context , the sfxt igr j17354@xmath03255 is a good bench test and we present intriguing hints likely suggesting that it is a transient gamma - ray source flaring on short timescales . if fully confirmed by further studies , the implications stemming are huge , both theoretically and observationally , and would add a further extreme characteristic to the already extreme class of sfxts . . And you have already written the first three sentences of the full article: during the last few years , agile and fermi observations of the galactic plane have indicated the existence of a possible population of unidentified transient mev - gev sources characterized by flares lasting no more than a few days at most e.g. @xcite , @xcite . notably , no blazar - like counterparts are known within their error boxes so they could represent a completely new class of galactic high energy transients . the task of identifying their counterparts at lower energies is very challenging , mainly because of their fast transient nature and large positional uncertainty ( e.g radii typically from 10 arcmin to 0.5 degrees ) .. Please generate the next two sentences of the article

however these difficulties are compensate by the fact that it is most probably within this group of gamma - ray sources that peculiar objects ( or even a new class of objects ) could emerge , leading to novel and unexpected discoveries . the ibis instrument onboard the integral satellite is particularly suited to search for reliable best candidate counterparts in the energy range 20100 kev thanks to i ) a large field of view ( 30@xmath1@xmath230@xmath1 ) which ensure a total coverage of the gamma - ray error box ii ) a good angular resolution ( 12 arcminutes ) which is mandatory to disentangle the hard x - ray emission of different sources in crowded fields such as those on the galactic plane iii ) a good sensitivity above 20 kev ( @xmath3 10 mcrab during a typical ibis observation lasting @xmath3 2,000 seconds ) . in particular ,

Suppose that you have an abstract for a scientific paper: we develop a formalism for the evaluation of conduction eigenchannels of atomic - sized contacts from first - principles . the multiple scattering korringa - kohn - rostoker ( kkr ) green s function method is combined with the kubo linear response theory . solutions of the eigenvalue problem for the transmission matrix are proven to be identical to eigenchannels introduced by landauer and bttiker . applications of the method are presented by studying ballistic electron transport through cu , pd , ni and co single - atom contacts . we show in detail how the eigenchannels are classified in terms of irreducible representations of the symmetry group of the system as well as by orbital contributions when the channels wave functions are projected on the contact atom . . And you have already written the first three sentences of the full article: the invention of the scanning tunneling microscope@xcite in 1981 and a consequent development in the beginning of the nineties of the remarkably simple experimental technique known as mechanically controllable break junction ( mcbj)@xcite led to the possibility of fabrication of metallic point contacts approaching the atomic scale . the recent review article ( ref . ) summarizes the numerous achievements in this field . in the experiments the conductance measured as a function of the elongation of the nanocontacts decreases in a stepwise fashion @xcite with steps of order of the conductance quantum @xmath0 . such behavior of the conductance is attributed to atomic rearrangements that entails a discrete variation of the contact diameter . @xcite the electron transport in metallic nanocontacts is purely ballistic and phase - coherent because their size is much smaller than all scattering lengths of the system .. Please generate the next two sentences of the article

according to landauer,@xcite conductance is understood as transport through nonmixing channels , @xmath1 where @xmath2 s are transmission probabilities . they are defined as eigenvalues of the transmission matrix @xmath3 . here

Suppose that you have an abstract for a scientific paper: the influence of gluon and goldstone boson induced tensor interactions on the dibaryon masses and d - wave decay widths has been studied in the quark delocalization , color screening model . the effective s - d wave transition interactions induced by gluon and goldstone boson exchanges decrease rapidly with increasing strangeness of the channel . the tensor contribution of k and @xmath0 mesons is negligible in this model . there is no six - quark state in the light flavor world studied so far that can become bound by means of these tensor interactions besides the deuteron . the partial d - wave decay widths of the @xmath1 n@xmath2 state to spin 0 and 1 @xmath3 final states are 12.0 kev and 21.9 kev respectively . this is a very narrow dibaryon resonance that might be detectable in relativistic heavy ion reactions by existing rhic detectors through the reconstruction of the vertex mass of the decay product @xmath3 and by the compas detector at cern or at jhf in japan and the fair project in germany in the future . . And you have already written the first three sentences of the full article: there might be two kinds of dibaryon@xcite . one is the loosely bound type consisting of two octet baryons ; the deuteron is a typical example . the others are tightly bound ; the @xmath4 particle had been predicted to be such a six quark state although later calculations cast doubt on it@xcite . instead , a non - strange @xmath5 @xmath6 and a strangeness -6 @xmath7 di-@xmath2 have been predicted to be tightly bound six quark states , which are formed from decuplet baryons@xcite . the strangeness -3 @xmath1 n@xmath2 has also been predicted to be of the tightly bound type@xcite .. Please generate the next two sentences of the article

the tensor interaction due to @xmath8 exchange plays a vital role in the formation of loosely bound deuteron . in the @xmath6 case the tensor interaction contribution to its mass is minor but is critical for its d - wave decay to the nn final state@xcite .

Suppose that you have an abstract for a scientific paper: we measure the mass functions for generically red and blue galaxies , using a @xmath0 sample of @xmath1 field galaxies from the galaxy and mass assembly ( gama ) survey . our motivation is that , as we show , the dominant uncertainty in existing measurements stems from how ` red ' and ` blue ' galaxies have been selected / defined . accordingly , we model our data as two naturally overlapping populations , each with their own mass function and colour mass relation , which enables us characterise the two populations without having to specify _ a priori _ which galaxies are ` red ' and ` blue ' . our results then provide the means to _ derive _ objective operational definitions for the terms ` red ' and ` blue ' , which are based on the phenomenology of the colour mass diagrams . informed by this descriptive modelling , we show that : 1 . ) after accounting for dust , the stellar colours of ` blue ' galaxies do not depend strongly on mass ; 2 . ) the tight , flat ` dead sequence ' does not extend much below @xmath2 ; instead , 3 . ) the stellar colours of ` red ' galaxies vary rather strongly with mass , such that lower mass ` red ' galaxies have bluer stellar populations ; 4 . ) below @xmath3 , the ` red ' population dissolves into obscurity , and it becomes problematic to talk about two distinct populations ; as a consequence , 5 . ) it is hard to meaningfully constrain the shape , including the existence of an upturn , of the ` red ' galaxy mass function below @xmath4 . points 14 provide meaningful targets for models of galaxy formation and evolution to aim for . galaxies : formation and evolution galaxies : mass functions galaxies : statistics galaxies : stellar content galaxies : fundamental parameters [ [ section ] ] _ `` all nature is perverse & will not do as i wish it '' _ + charles darwin ( 1855 ) . And you have already written the first three sentences of the full article: quantitative studies of galaxy demographics that is , of the multivariate distribution functions that connect global galaxy properties provide the empirical bedrock on which theoretical models of galaxy formation and evolution are founded . the quality of a cosmological model of galaxy formation ( _ e.g. _ * ? ? ? * ; * ? ? ?. Please generate the next two sentences of the article

* ; * ? ? ? * ; * ? ? ?

Suppose that you have an abstract for a scientific paper: we consider the one - factor model of commodities for which the parameters of the model depend upon the stock price or on the time . for that model we study the existence of group - invariant transformations . when the parameters are constant , the one - factor model is maximally symmetric . that also holds for the time - dependent problem . however , in the case for which the parameters depend upon the stock price ( space ) the one - factor model looses the group invariants . for specific functional forms of the parameters the model admits other possible lie algebras . in each case we determine the conditions which the parameters should satisfy in order for the equation to admit lie point symmetries . some applications are given and we show which should be the precise relation amongst the parameters of the model in order for the equation to be maximally symmetric . finally we discuss some modifications of the initial conditions in the case of the space - dependent model . we do that by using geometric techniques . * keywords : * lie point symmetries ; one - factor model ; prices of commodities * msc 2010 : * 22e60 ; 35q91 . And you have already written the first three sentences of the full article: three models which study the stochastic behaviour of the prices of commodities that take into account several aspects of possible influences on the prices were proposed by e schwartz @xcite in the late nineties . in the simplest model ( the so - called one - factor model ) schwartz assumed that the logarithm of the spot price followed a mean - reversion process of ornstein uhlenbeck type . the one - factor model is expressed by the following @xmath0 evolution equation@xmath1where @xmath2 measures the degree of mean reversion to the long - run mean log price , @xmath3 is the market price of risk , @xmath4 is the standard deviation of the return on the stock , @xmath5 is the stock price , @xmath6 is the drift rate of @xmath5 and @xmath7 is the time .. Please generate the next two sentences of the article

@xmath8 is the current value of the futures contract which depends upon the parameters @xmath9 , _ i.e. _ , @xmath10 .

Suppose that you have an abstract for a scientific paper: we have successfully used a fast electronic feed forward to increase the success probability of a linear optical implementation of a programmable phase gate from 25% to its theoretical limit of 50% . the feed forward applies a conditional unitary operation which changes the incorrect output states of the data qubit to the correct ones . the gate itself rotates an arbitrary quantum state of the data qubit around the @xmath0-axis of the bloch sphere with the angle of rotation being fully determined by the state of the program qubit . the gate implementation is based on fiber optics components . qubits are encoded into spatial modes of single photons . the signal from the feed - forward detector is led directly to a phase modulator using only a passive voltage divider . we have verified the increase of the success probability and characterized the gate operation by means of quantum process tomography . we have demonstrated that the use of the feed forward does not affect either the process fidelity or the output - state fidelities . . And you have already written the first three sentences of the full article: linear - optical architectures belong to the most prominent platforms for realizing protocols of quantum information processing @xcite . they are experimentally feasible and they work directly with photons without the necessity to transfer the quantum state of a photonic qubit into another quantum system like an ion etc . the latter feature is quite convenient because photons are good carriers of information for communication purposes .. Please generate the next two sentences of the article

linear - optical quantum gates achieve the non - linearity necessary for the interaction between qubits by means of the non - linearity of quantum measurement . unfortunately , quantum measurement is not only non - linear but also probabilistic . therefore linear - optical implementations of quantum gates are mostly probabilistic too their operation sometimes fails .

Suppose that you have an abstract for a scientific paper: in this paper , we introduce a new distribution generated by lindley random variable which offers a more flexible model for modelling lifetime data . various statistical properties like distribution function , survival function , moments , entropy , and limiting distribution of extreme order statistics are established . inference for a random sample from the proposed distribution is investigated and maximum likelihood estimation method is used for estimating parameters of this distribution . the applicability of the proposed distribution is shown through real data sets . * keyword : * lindley distribution , entropy , stress - strength reliability model , maximum likelihood estimator . + * ams 2001 subject classification : * 60e05 . And you have already written the first three sentences of the full article: lifetime distribution represents an attempt to describe , mathematically , the length of the life of a system or a device . lifetime distributions are most frequently used in the fields like medicine , engineering etc . many parametric models such as exponential , gamma , weibull have been frequently used in statistical literature to analyze lifetime data .. Please generate the next two sentences of the article

but there is no clear motivation for the gamma and weibull distributions . they only have more general mathematical closed form than the exponential distribution with one additional parameter .

Suppose that you have an abstract for a scientific paper: a `` hybrid method '' , dedicated to asymptotic coefficient extraction in combinatorial generating functions , is presented , which combines darboux s method and singularity analysis theory . this hybrid method applies to functions that remain of moderate growth near the unit circle and satisfy suitable smoothness assumptions this , even in the case when the unit circle is a natural boundary . a prime application is to coefficients of several types of infinite product generating functions , for which full asymptotic expansions ( involving periodic fluctuations at higher orders ) can be derived . examples relative to permutations , trees , and polynomials over finite fields are treated in this way . . And you have already written the first three sentences of the full article: a few enumerative problems of combinatorial theory lead to generating functions that are expressed as infinite products and admit the unit circle as a natural boundary . functions with a fast growth near the unit circle are usually amenable to the saddle point method , a famous example being the integer partition generating function . we consider here functions of moderate growth , which are outside the scope of the saddle point method . we do so in the case where neither singularity analysis nor darboux s method is directly applicable , but the function to be analysed can be factored into the product of an elementary function with isolated singularities and a sufficiently smooth factor on the unit circle .. Please generate the next two sentences of the article

such decompositions are often attached to infinite products exhibiting a regular enough structure and are easily obtained by the introduction of suitable convergence factors . under such conditions , we prove that coefficients admit full asymptotic expansions involving powers of logarithms and descending powers of the index @xmath0 , as well as periodically varying coefficients .

Suppose that you have an abstract for a scientific paper: electric field gradient effects induced by an asymmetrically in - plane shaped gaas / algaas modulation - doped structures of various design are investigated within 4300 k temperature range . it is demonstrated that current voltage characteristics of such structures at low , 480 k , temperatures exhibit well - pronounced asymmetry arising due to a presence of two different gradients of the electric field in a two dimensional electron gas . this phenomenon is caused by both , different accumulation of two - dimensional electrons due to asymmetrical shape of the structure and nonlocality in the electron drift velocity . experiments are illustrated by a phenomenological model and monte carlo simulation . possible applications of the effect to detect electromagnetic radiation of ghz and thz frequencies are discussed as well . 1.0 truecm . And you have already written the first three sentences of the full article: as it is known , in modulation - doped ( or selectively - doped ) structures free electrons , spatially separated from ionized donors , are confined to a narrow potential well forming the so - called two - dimensional electron gas ( 2deg)@xcite . @xmath0 the @xmath1 axis , i. e. perpendicular to the 2deg plane , the confinement potential has a triangular shape , and the spectrum of the 2deg is composed of a sequence of quantum subbands.@xcite the shape of the confining potential has influence only to the carrier transitions between different subbands ; meanwhile for excitations within each subband so - called intraband excitations this effect is very small . @xmath2 to the @xmath1 axis , i. e. in the 2deg , or @xmath3 plane , the carriers display very high electron mobilities exceeding values of 2@xmath4/(v@xmath5s ) at liquid nitrogen and 1@xmath6/(v@xmath5s ) at liquid helium temperatures.@xcite this fundamental property of these structures allowed to invent hemts high electron mobility transistors.@xcite the carrier transport in 2deg layers at low electric fields is described by the ohm s law together with the einstein relation for the diffusion coefficient , i.e. @xmath7 , \end{aligned}\ ] ] where @xmath8 is drift velocity , @xmath9 stands for electron mobility , @xmath10 is the electric field and @xmath11 is the free carrier concentration ; @xmath12 is the electron charge , @xmath13 and @xmath14 denote boltzmann constant and lattice temperature , respectively .. Please generate the next two sentences of the article

this so - called `` drift - diffusion equation '' describes the quasi - classical situation when the quantization of the electronic states - induced effects are not important . on the other hand , it does not take into account the hot - electrons phenomena when the applied in - plane electric field is strong enough to heat the electrons up to the energy exceeding their equilibrium value.@xcite the electric field in modelling , as a rule , is assumed to be uniform .

Suppose that you have an abstract for a scientific paper: the hypothesis is discussed that muon bundles of extremaly high multiplicity observed recently by aleph detector ( in the dedicated cosmic - ray run ) can originate from the strangelets colliding with the atmosphere . . And you have already written the first three sentences of the full article: in the astrophysical literature @xcite one can find a number of phenomena which can be regarded as a possible manifestation of the existence of the so called _ strange quark matter _ ( sqm ) ( in the form of lumps called strangelets ) , extremaly interesting possibility of a possible new stable form of matter . they include , among others , anomalous cosmic ray burst from _. Please generate the next two sentences of the article

cygnus x-3 _ , extraordinary high luminosity gamma - ray bursts from the _ supernova remnant n49 _ in the large magellanic cloud or _ centauro _ type events .

Suppose that you have an abstract for a scientific paper: the transition from the near to the far field of the fundamental mode radiating out of a photonic crystal fiber is investigated experimentally and theoretically . it is observed that the hexagonal shape of the near field rotates two times by @xmath0 when moving into the far field , and eventually six satellites form around a nearly gaussian far - field pattern . a semi - empirical model is proposed , based on describing the near field as a sum of seven gaussian distributions , which qualitatively explains all the observed phenomena and quantitatively predicts the relative intensity of the six satellites in the far field . 10 opt . express * 9 * , 674779 ( 2001 ) , http://www.opticsexpress.org/issue.cfm?issue id=124 . j. opt . a : pure appl . opt . * 3 * , s103s207 ( 2001 ) . j. c. knight and p. s. j. russell , `` applied optics : new ways to guide light , '' _ science _ * 296 * , 276277 ( 2002 ) . j. c. knight , t. a. birks , p. s. j. russell , and d. m. atkin , `` all - silica single - mode optical fiber with photonic crystal cladding , '' _ opt . lett . _ * 21 * , 15471549 ( 1996 ) . j. c. knight , t. a. birks , p. s. j. russell , and d. m. atkin , `` all - silica single - mode optical fiber with photonic crystal cladding : errata , '' _ opt . lett . _ * 22 * , 484485 ( 1997 ) . j. c. knight , j. broeng , t. a. birks , and p. s. j. russell , `` photonic band gap guidance in optical fibers , '' _ science _ * 282 * , 14761478 ( 1998 ) . r. f. cregan , b. j. mangan , j. c. knight , t. a. birks , p. s. j. russell , p. j. roberts , and d. c. allan , `` single - mode photonic band gap guidance of light in air , '' _ science _ * 285 * , 15371539 ( 1999 ) . t. a. birks , j. c. knight , and p. s. j. russell , `` endlessly single mode photonic crystal fibre , '' _ opt . lett . _ * 22 * , 961963 ( 1997 ) . j. broeng , d. mogilevstev , s. e. barkou , and a. bjarklev , `` photonic crystal fibers : a new class of.... And you have already written the first three sentences of the full article: photonic crystal fibers ( pcf ) are a new class of optical fibers which has revealed many surprising phenomena and also holds a big promise for future applications ( see _ e.g. _ these pcfs are made from pure silica with a cladding consisting of a regular lattice of air - holes running along the fiber axis . depending on the arrangement of the air - holes the guiding of light can be provided by either modified total internal reflection @xcite or by the photonic band - gap effect @xcite and pcfs can even be endlessly single - mode @xcite because of the wavelength dependence of the cladding index . for the basic operation we refer to the review of broeng _ et al . _. Please generate the next two sentences of the article

@xcite . understanding the shape and radiation pattern , as illustrated in fig .

Suppose that you have an abstract for a scientific paper: in this paper , we examine in detail the key structural properties of high redshift dark matter haloes as a function of their spin parameter . we perform and analyze high resolution cosmological simulations of the formation of structure in a lcdm universe . we study the mass function , shapes , density profiles , and rotation curves for a large sample of dark matter haloes from @xmath0 . we also present detailed convergence tests for individual haloes . we find that high spin haloes have stronger clustering strengths ( up to @xmath1 ) at all mass and redshift ranges at these early epochs . high redshift spherical haloes are also up to @xmath2 more clustered than extremely aspherical haloes . high spin haloes at these redshifts are also preferentially found in high density environments , and have more neighbors than their low spin counterparts . we report a systematic offset in the peak of the circular velocity curves for high and low spin haloes of the same mass . therefore , estimating halo masses without knowledge of the spin , using only the circular velocity can yield errors of up to @xmath3 . the significant dependence of key structural properties on spin that we report here likely has important implications for studies of star formation and feedback from these galaxies . cosmology : dark matter cosmology : early universe galaxies : high - redshift galaxies : formation . And you have already written the first three sentences of the full article: the currently favored model that describes the formation of structure in the universe is the @xmath4 cold dark matter ( lcdm ) paradigm . in this model , the initial density distribution of the universe was nearly homogenous , with small gaussian density perturbations imprinted during an inflationary epoch . these fluctuations expand linearly , until the over - dense regions undergo non - linear gravitational collapse to form bound dark matter haloes .. Please generate the next two sentences of the article

these haloes form in a hierarchical fashion : small haloes form first , and then larger ones assemble later via merging . in the lcdm paradigm , baryons follow the dark matter .

Suppose that you have an abstract for a scientific paper: direct observation of vortices by the scanning squid microscopy was made on large mesoscopic disks of an amorphous moge thin film . owing to the weak pinning nature of the amorphous film , vortices are able to form geometry induced , ( quasi-)symmetric configurations of polygons and concentric shells in the large disks . systematic measurements made on selected disks allow us to trace not only how the vortex pattern evolves with magnetic field , but also how the vortex polygons change in size and rotate with respect to the disk center . the results are in good agreement with theoretical considerations for mesoscopic disks with sufficiently large diameter . a series of vortex images obtained in a disk with a pinning site reveals a unique line symmetry in vortex configurations , resulting in modifications of the shell filling rule and the magic number . # 1@xmath0#1 2 . And you have already written the first three sentences of the full article: tiny superconductors , accommodating only a few quantized magnetic flux lines , display a great variety of vortex structure different from the abrikozov vortex lattice in bulk superconductors @xcite . examples include vortex polygons and concentric vortex rings called `` vortex shells '' , which are stable configurations of the repulsive flux lines under the geometrical confinement via the influence of the screening current flowing along the sample edge . the issue of vortex matter confined into small superconductors has been studied theoretically and numerically for many years , focusing mainly on how the vortices are distributed in disk @xcite@xcite@xcite@xcite@xcite@xcite , square @xcite , and triangle shaped small superconductors @xcite . several studies reveal the field evolutions of the vortex structure in small superconductors , and argue which vortex configurations are energetically favorable and how the transition between different vortex states occurs . the obtained rule of shell filling and magic number configurations for consecutive new shells are relevant to phenomena observed in other systems , including the puzzling nucleation of vortices observed in rotating condensates of superfluid @xmath1he @xcite and cold dilute alkali - metal gases @xcite . the experimental investigations for vortex states in small superconductors were initiated by hall magnetometer measurements @xcite@xcite , followed by a multiple - small tunneling junction measurement @xcite .. Please generate the next two sentences of the article

kinks in the magnetization or jumps in the tunneling spectra mark transitions of vortex states in small superconducting dots . they evidence changes of vorticity @xmath2 ( the number of vortices ) , not actual distributions of vortices in the dots .

Suppose that you have an abstract for a scientific paper: we consider a system of two interpenetrating bose - einstein condensates of atoms in two different hyperfine spin states . we show that in the presence of a small coupling drive between the two spin levels , there exist domain walls across which the relative phase of the two condensates changes by @xmath0 . we give the physical interpretation of such walls . we show that the wall tension determines the force between certain pairs of vortices at large distances . we also show that the probability of the spontaneous decay of the domain wall is exponentially suppressed , both at finite and at zero temperature , and determine the exponents in the regime of small rabi frequency . we briefly discuss how such domain walls could be created in future experiments . . And you have already written the first three sentences of the full article: one of the long - sought goals in low - temperature physics is the creation of two interpenetrating superfluids . early efforts were directed at mixtures of helium isotopes . more recently , following the experiments with bose - einstein condensates ( bec ) of atomic gases @xcite , considerable efforts have been made to create systems where two species of atoms condense simultaneously .. Please generate the next two sentences of the article

this goal was partially achieved for two different hyperfine spin states of @xmath1rb , which were condensed in the same trap by the technique of sympathetic cooling @xcite . later the dynamics of the complex relative motion of the condensates has been studied @xcite .

Suppose that you have an abstract for a scientific paper: motivated by recent financial crises significant research efforts have been put into studying contagion effects and herding behaviour in financial markets . much less has been said about influence of financial news on financial markets . we propose a novel measure of collective behaviour in financial news on the web , news cohesiveness index ( nci ) , and show that it can be used as a systemic risk indicator . we evaluate the nci on financial documents from large web news sources on a daily basis from october 2011 to july 2013 and analyse the interplay between financial markets and financially related news . we hypothesized that strong cohesion in financial news reflects movements in the financial markets . cohesiveness is more general and robust measure of systemic risk expressed in news , than measures based on simple occurrences of specific terms . our results indicate that cohesiveness in the financial news is highly correlated with and driven by volatility on the financial markets . = 1 . And you have already written the first three sentences of the full article: with the growth of internet the relationship between online information and financial markets has become a subject of ever increasing interest . online information offers with respect to its origin and purpose and reflects either interest of some profile of users in the form of query or knowledge about certain topic in the form of news blogs or reports . financial markets are strongly information - driven and these effects can be seen by studying either search query volumes or social media sentiment .. Please generate the next two sentences of the article

many studies have analysed the effects of search query volumes of specific terms with movements in financial markets of related items @xcite . bordino et al .

Suppose that you have an abstract for a scientific paper: we present , using the statistical model , an analysis of the production of light nuclei , hypernuclei and their antiparticles in central collisions of heavy nuclei . based on these studies we provide predictions for the production yields of multiply - strange light nuclei . , , , . And you have already written the first three sentences of the full article: one of the major goals of ultrarelativistic nuclear collision studies is to obtain information on the qcd phase diagram @xcite . currently , one of the most direct approaches is the investigation of hadron production . hadron yields measured in central heavy ion collisions from ags up to rhic energies can be described very well @xcite within a hadro - chemical equilibrium model . in our approach. Please generate the next two sentences of the article

@xcite the only parameters are the chemical freeze - out temperature @xmath0 and the baryo - chemical potential @xmath1 ( and the fireball volume @xmath2 , in case yields rather than ratios of yields are fitted ) . other approaches @xcite employ ( several ) other , non - thermal , parameters . for a review see @xcite .

Suppose that you have an abstract for a scientific paper: we study heat conduction in ( @xmath0 , 0)/(2@xmath0 , 0 ) intramolecular junctions by using molecular dynamics method . it is found that the heat conduction is asymmetric , namely , heat transports preferably in one direction . this phenomenon is also called thermal rectification . the rectification is weakly dependent on the detailed structure of connection part , but is strongly dependent on the temperature gradient . we also study the effect of the tube radius and intramolecular junction length on the rectification . our study shows that the tensile stress can increase rectification . the physical mechanism of the rectification is explained . . And you have already written the first three sentences of the full article: in past two decades , the study of heat conduction in low dimensional model systems has enriched our understanding on heat conduction from microscopic point of view@xcite . in turn , the study has also lead to some interesting inventions for heat control and management devices . for example , the heat conduction in nonlinear lattice models @xcite demonstrates rectification phenomenon , namely , heat flux can flow preferably in one direction .. Please generate the next two sentences of the article

furthermore , the _ negative differential thermal resistance _ is also found and based on which , a thermal transistor model has been constructed.@xcite most recently , the two segment model of thermal rectifier proposed in ref has been experimentally realized by using gradual mass - loaded carbon and boron nitride nanotubes.@xcite these works have opened a new era for heat management and heat control in microscopic level . on the other hand , there have been increasing studies on heat conduction in real nano scale systems@xcite .

Suppose that you have an abstract for a scientific paper: we study the ground state phase diagram of a mixture of bosonic and fermionic cold atoms confined on two- and three - dimensional optical lattices . the coupling between bosonic fluctuations and fermionic atoms can be attractive or repulsive and has similarities with electron - phonon coupling in crystals . we investigate behavior of the mixtures in the limit , where the bogoliubov sound velocity that dictates bosonic dynamics is comparable to the fermi velocity , hence the retardation effects are important part of the physics . the dynamic lindhard response function of the fermionic density to changes in the bosonic number of particles above some critical frequency can alter the sign and in consequence the inter - species interaction between particles becomes repulsive in contrast to the static limit ( instantaneous and always attractive ) . considering the above we show that the structure of the phase diagrams crucially depends on the difference in masses of the bosons and fermions . we discuss the situations where integrating out fermionic field provides an additional interaction that can decrease or increase bosonic coherence . . And you have already written the first three sentences of the full article: trapping and cooling bose - fermi mixtures of dilute quantum gases has opened a wide area of research in atomic physics . the interactions between bosonic and fermionic species interconnect two systems of fundamentally different quantum statistics . the diluteness of the gaseous mixtures allows one to treat the interactions between particles in terms of binary collisions . in consequence. Please generate the next two sentences of the article

we can replace the real inter - atomic potential by a pseudo - potential characterized by only one parameter , the @xmath0-scattering length . the latter is experimentally@xcite tunable by exploiting optically or magnetically induced feshbach resonances@xcite . despite its simplicity the interaction potential ( mathematically ill defined@xcite ) of the ultra - cold multi - component gases confined in optical lattices

Suppose that you have an abstract for a scientific paper: we are dealing with two - dimensional gravitational anomalies , specifically with the einstein anomaly and the weyl anomaly , and we show that they are fully determined by dispersion relations independent of any renormalization procedure ( or ultraviolet regularization ) . the origin of the anomalies is the existence of a superconvergence sum rule for the imaginary part of the relevant formfactor . in the zero mass limit the imaginary part of the formfactor approaches a @xmath0-function singularity at zero momentum squared , exhibiting in this way the infrared feature of the gravitational anomalies . we find an equivalence between the dispersive approach and the dimensional regularization procedure . the schwinger terms appearing in the equal time commutators of the energy momentum tensors can be calculated by the same dispersive method . although all computations are performed in two dimensions the method is expected to work in higher dimensions too . . And you have already written the first three sentences of the full article: an anomaly in field theory occurs if a symmetry of the action or the corresponding conservation law , valid in the classical theory , is violated in the quantized version . this surprising feature of quantum theory discovered by adler @xcite , bell and jackiw @xcite , and by bardeen @xcite in 1969 plays a fundamental role in physics ( for details see refs.@xcite @xcite ) . physically there is a difference between external and internal symmetries .. Please generate the next two sentences of the article

the breakdown of an external symmetry is not dangerous for the consistency of the theory , on the contrary , it provides for instance the physical explanation for the @xmath1-decay @xcite , @xcite or the solution to the @xmath2 problem in qcd @xcite . on the other hand , the breakdown of an internal symmetry ( i.e. gauge symmetry ) leads to an inconsistency of the quantum theory , the anomalous ward identities destroy the renormalizability of the theory @xcite , and also the unitarity of the @xmath3-matrix may be lost @xcite . to avoid such anomalies imposes severe restrictions to the physical content of a theory .

Suppose that you have an abstract for a scientific paper: the tidal torque exerted by a protoplanetary disk with power law surface density and temperature profiles onto an embedded protoplanetary embryo is generally a negative quantity that leads to the embryo inwards migration . here we investigate how the tidal torque balance is affected at a disk surface density radial jump . the jump has two consequences : * it affects the differential lindblad torque . in particular if the disk is merely empty on the inner side , the differential lindblad torque almost amounts to the large negative outer lindblad torque . * it affects the corotation torque , which is a quantity very sensitive to the local gradient of the disk surface density . in particular if the disk is depleted on the inside and if the jump occurs radially over a few pressure scale - heights , the corotation torque is a positive quantity that is much larger than in a power - law disk . we show by means of customized numerical simulations of low mass planets embedded in protoplanetary nebulae with a surface density jump that the second effect is dominant , that is that the corotation torque largely dominates the differential lindblad torque on the edge of a central depletion , even a shallow one . namely , a disk surface density jump of about @xmath0 % over @xmath1 disk thicknesses suffices to cancel out the total torque . as a consequence the type i migration of low mass objects reaching the jump should be halted , and all these objects should be trapped there provided some amount of dissipation is present in the disk to prevent the corotation torque saturation . as dissipation is provided by turbulence , which induces a jitter of the planet semi - major axis , we investigate under which conditions the trapping process overcomes the trend of turbulence to induce stochastic migration across the disk . we show that a cavity with a large outer to inner surface density ratio efficiently traps embryos from @xmath2 to @xmath3 @xmath4 , at any radius up to @xmath5 au from the central.... And you have already written the first three sentences of the full article: the migration of low mass protoplanets ( @xmath7 ) under the action of disk tides is long known to be a fast process in disks with power law surface density profiles @xcite . the fast migration timescale estimates of these objects even constitutes a bottleneck for the core accretion scenario , which implies a slow build up of a solid core until it reaches the mass threshold ( @xmath8 ) above which rapid gas accretion begins . indeed , the solid core build up time is @xmath9 yrs @xcite , while the migration timescale of a @xmath10 planet is @xmath11 yrs @xcite and scales inversely proportionally to the planet mass .. Please generate the next two sentences of the article

the existence of gaseous giant planets at large distances ( @xmath12 au ) from their central star therefore constitutes a puzzle . recent work by @xcite has shown that the core build up time scale can be lowered by taking migration into account , which prevents the depletion of the core feeding zone . however , these authors find that the most up to date type i migration timescale estimate , which includes three dimensional effects and the co - rotation torque @xcite , still needs to be lowered by a factor @xmath13 in order to allow for the solid core survival

Suppose that you have an abstract for a scientific paper: trigonometric formulas are derived for certain families of associated legendre functions of fractional degree and order , for use in approximation theory . these functions are algebraic , and when viewed as gauss hypergeometric functions , belong to types classified by schwarz , with dihedral , tetrahedral , or octahedral monodromy . the dihedral legendre functions are expressed in terms of jacobi polynomials . for the last two monodromy types , an underlying ` octahedral ' polynomial , indexed by the degree and order and having a non - classical kind of orthogonality , is identified , and recurrences for it are worked out . it is a ( generalized ) heun polynomial , not a hypergeometric one . for each of these families of algebraic associated legendre functions , a representation of the rank-@xmath0 lie algebra @xmath1 is generated by the ladder operators that shift the degree and order of the corresponding solid harmonics . all such representations of @xmath1 are shown to have a common value for each of its two casimir invariants . the dirac singleton representations of @xmath2 are included . . And you have already written the first three sentences of the full article: the first - kind associated legendre functions @xmath3 , or the ferrers versions @xmath4 , are classical . ( @xmath3 and @xmath4 are continuations of each other , with respective real domains @xmath5 and @xmath6 . ) the roles they play when the degree @xmath7 and order @xmath8 equal integers @xmath9 are familiar . the legendre , or ferrers polynomials @xmath10 , @xmath11 , are orthogonal on @xmath12 $ ] and are used in series expansions .. Please generate the next two sentences of the article

the spherical harmonics @xmath13 are orthogonal on the symmetric space @xmath14 , and appear in harmonic analysis based on the lie group @xmath15 . it is less well known that ferrers functions @xmath4 of a fixed order @xmath8 , and degrees that may be non - integral but are spaced by integers , can also be used in series expansions .

Suppose that you have an abstract for a scientific paper: we define the notion of a finite - time singularity of a vector field and then discuss a technique suitable for the asymptotic analysis of vector fields and their integral curves in the neighborhood of such a singularity . having in mind the application of this method to cosmology , we also provide an analysis of the time singularities of an isotropic universe filled with a perfect fluid in general relativity . . And you have already written the first three sentences of the full article: there are two approaches to characterizing spacetime singularities in a cosmological context . the first approach may be called _ geometric _ and consists of finding sufficient and/or necessary conditions for singularity formation , or absence , _ independently _ of any specific solution of the field equations under general conditions on the matter fields . methods of this sort include those based on an analysis of geodesic congruences in spacetime and lead to the well known singularity theorems , cf .. Please generate the next two sentences of the article

@xcite , as well as those which are depend on an analysis of the geodesic equations themselves and lead to completeness theorems such as those expounded in cbc02 , and the classification of singularities in @xcite . the second approach to the singularity problem can be termed _ dynamical _ and refers to characterizing cosmological singularities in a geometric theory of gravity by analysing the dynamical field equations of the theory _ _ _ _ it uses methods from the theory of dynamical systems and can be _ global _ , referring to the asymptotic behaviour of the system of field equations for large times , or _ local _ , giving the behaviour of the field components in a small neighborhood of the finite - time singularity . in this latter spirit

Suppose that you have an abstract for a scientific paper: we compute the magnetocrystalline anisotropy energy within two - dimensional rashba models . for a ferromagnetic free - electron rashba model , the magnetic anisotropy is exactly zero regardless of the strength of the rashba coupling , unless only the lowest band is occupied . for this latter case , the model predicts in - plane anisotropy . for a more realistic rashba model with finite band width , the magnetic anisotropy evolves from in - plane to perpendicular and back to in - plane as bands are progressively filled . this evolution agrees with first - principles calculations on the interfacial anisotropy , suggesting that the rashba model captures energetics leading to anisotropy originating from the interface provided that the model takes account of the finite brillouin zone . the results show that the electron density modulation by doping or an external voltage is more important for voltage - controlled magnetic anisotropy than the modulation of the rashba parameter . . And you have already written the first three sentences of the full article: recent developments in the design of spintronic devices favor perpendicular magnetization , increasing the interest in materials with perpendicular magnetic anisotropy @xcite . one advantage is that devices with the same thermal stability can be switched more easily if the magnetization is perpendicular than if it is in plane @xcite . since magnetostatic interactions favor in - plane magnetization for a thin film geometry , perpendicular magnetic anisotropy requires materials and interfaces that have strong magnetocrystalline anisotropy .. Please generate the next two sentences of the article

numerous computational studies @xcite show the importance of interfaces on magnetocrystalline anisotropy . the theory developed by bruno @xcite provides an insightful explanation of the surface magnetocrystalline anisotropy originating from spin - orbit coupling and the theory has been confirmed by experiments @xcite .

Suppose that you have an abstract for a scientific paper: this paper revisits the classical kennicutt method for inferring the stellar initial mass function ( imf ) from the integrated light properties of galaxies . the large size , uniform high quality data set from the sloan digital sky survey dr4 is combined with more in depth modeling and quantitative statistical analysis to search for systematic imf variations as a function of galaxy luminosity . galaxy h@xmath0 equivalent widths are compared to a broadband color index to constrain the imf . this parameter space is useful for breaking degeneracies which are traditionally problematic . age and dust corrections are largely orthogonal to imf variations . in addition the effects of metallicity and smooth star formation history e - folding times are small compared to imf variations . we find that for the sample as a whole the best fitting imf slope above 0.5 @xmath1 is @xmath2 with a negligible random error of @xmath3 and a systematic error of @xmath4 . galaxies brighter than around @xmath5 ( including galaxies like the milky way which has @xmath6 ) are well fit by a universal @xmath7 imf , similar to salpeter , and smooth , exponential star formation histories ( sfh ) . fainter galaxies prefer steeper imfs and the quality of the fits reveal that for these galaxies a universal imf with smooth sfhs is actually a poor assumption . several sources of sample bias are ruled out as the cause of these luminosity dependent imf variations . analysis of bursting sfh models shows that an implausible coordination of burst times is required to fit a universal imf to the @xmath8 galaxies . this leads to the conclusions that the imf in low luminosity galaxies has fewer massive stars , either by steeper slope or lower upper mass cutoff , and is not universal . . And you have already written the first three sentences of the full article: a precise measurement of the stellar initial mass function ( imf ) and its functional dependence on environmental conditions would impact astronomy over a wide range of physical scales . it would be of great help to theorists in untangling the mysteries of star formation and it is a key input in spectral synthesis models used to interpret the observed properties of galaxies both nearby and in the early universe . the current question is whether the imf is _ universal_ the same regardless of time and environmental conditions .. Please generate the next two sentences of the article

@xcite concisely states the current understanding of imf universality . it is difficult to believe that the imf is universal given the diversity of galaxy types , environments , star formation rates , and populations within galaxies over the range of observable lookback times . on the other hand , while imf measurements do vary they are all consistent with a universal imf within measurement errors and sampling statistics . the only way to proceed then is to strive for smaller measurement errors and improving sample sizes . a definitive theoretical derivation of the imf does not yet exist .

Suppose that you have an abstract for a scientific paper: ste - quest is a fundamental science mission which is considered for launch within the cosmic vision programme of the european space agency ( esa ) . its main scientific objectives relate to probing various aspects of einstein s theory of general relativity by measuring the gravitational red - shift of the earth , the moon and the sun as well as testing the weak equivalence principle to unprecedented accuracy . in order to perform the measurements , the system features a spacecraft equipped with two complex instruments , an atomic clock and an atom interferometer , a ground - segment encompassing several ground - terminals collocated with the best available ground atomic clocks , and clock comparison between space and ground via microwave and optical links . the baseline orbit is highly eccentric and exhibits strong variations of incident solar flux , which poses challenges for thermal and power subsystems in addition to the difficulties encountered by precise - orbit - determination at high altitudes . the mission assessment and definition phase ( phase - a ) has recently been completed and this paper gives a concise overview over some system level results . . And you have already written the first three sentences of the full article: space time explorer & quantum equivalence space test ( ste - quest ) is a medium - sized mission candidate for launch in 2022/2024 in the cosmic vision programme of the european space agency . after recommendation by the space science advisory committee , it was selected to be first studied by esa , followed by two parallel industrial assessment studies . this paper gives a brief summary of the assessment activities by astrium which build on and extend the preceding esa study as described in@xcite .. Please generate the next two sentences of the article

ste - quest aims to study the cornerstones of einstein s equivalence principle ( eep ) , pushing the limits of measurement accuracy by several orders of magnitude compared to what is currently achievable in ground based experiments@xcite . on the one hand , experiments are performed to measure the gravitational red - shift experienced by highly accurate clocks in the gravitational fields of earth or sun ( space time explorer ) . on the other hand , differential accelerations of microscopic quantum particles

Suppose that you have an abstract for a scientific paper: the magnetospheric locations of pulsar radio emission region are not well known . the actual form of the so called radius to frequency mapping should be reflected in the aberration retardation ( a / r ) effects that shift and/or delay the photons depending on the emission height in the magnetosphere . recent studies suggest that in a handful of pulsars the a / r effect can be discerned w.r.t the peak of the central core emission region . to verify these effects in an ensemble of pulsars we launched a project analysing multi frequency total intensity pulsar profiles obtained from the new observations from the giant meterwave radio telescope ( gmrt ) , arecibo observatory ( ao ) and archival european pulsar network ( epn ) data . for all these profiles we measure the shift of the outer cone components with respect to the core component which is necessary for establishing the a / r effect . within our sample of 23 pulsars 7 show the a / r effects , 12 of them ( doubtful cases ) show a tendency towards this effect , while the remaining 4 are obvious counter examples . the counter examples and doubtful cases may arise from uncertainties in determination of the location of the meridional plane and/or the core emission component . it hence appears that the a / r effects are likely to operate in most pulsars from our sample . we conclude that in cases where those effects are present the core emission has to originate below the conal emission region . [ firstpage ] pulsars : general stars : neutron radiation mechanisms : non - thermal methods : data analysis . And you have already written the first three sentences of the full article: aberration and retardation effects ( a / r hereafter ) can be observed in a pulsar profile as a shift of the position of conal components with respect to the core component towards earlier longitudinal phases ( see for e.g. malov & suleimanova ( 1998 ) , gangadhara & gupta 2001 , g&ga hereafter ) . such effects should occur if different components are emitted at different distances from the pulsar surface ( emission radii ) , as well as from the pulsar spin axis . aberration is caused by bending of radiation beam due to the polar cap rotation , while retardation is based on a path difference for radiation from different conal emission regions to reach an observer .. Please generate the next two sentences of the article

if we assume that the emission from the core component arises relatively close to the star surface , then it should not be strongly affected by either of the two above mentioned effects . this will be our initial assumption . to determine a / r shifts the pulsar profile has to meet certain requirements .

Suppose that you have an abstract for a scientific paper: despite astrophysical importance of binary star systems , detections are limited to those located in small ranges of separations , distances , and masses and thus it is necessary to use a variety of observational techniques for a complete view of stellar multiplicity across a broad range of physical parameters . in this paper , we report the detections and measurements of 2 binaries discovered from observations of microlensing events moa-2011-blg-090 and ogle-2011-blg-0417 . determinations of the binary masses are possible by simultaneously measuring the einstein radius and the lens parallax . the measured masses of the binary components are 0.43 @xmath0 and 0.39 @xmath0 for moa-2011-blg-090 and 0.57 @xmath0 and 0.17 @xmath0 for ogle-2011-blg-0417 and thus both lens components of moa-2011-blg-090 and one component of ogle-2011-blg-0417 are m dwarfs , demonstrating the usefulness of microlensing in detecting binaries composed of low - mass components . from modeling of the light curves considering full keplerian motion of the lens , we also measure the orbital parameters of the binaries . the blended light of ogle-2011-blg-0417 comes very likely from the lens itself , making it possible to check the microlensing orbital solution by follow - up radial - velocity observation . for both events , the caustic - crossing parts of the light curves , which are critical for determining the physical lens parameters , were resolved by high - cadence survey observations and thus it is expected that the number of microlensing binaries with measured physical parameters will increase in the future . . And you have already written the first three sentences of the full article: binary star systems are of astrophysical importance for various reasons . first , they compose an important portion of stars in the galaxy @xcite and thus theories about stellar formation and evolution should account for the binary nature of stars . second , binary stars allow us to directly measure the masses of their component stars . the determined masses in turn allow other stellar parameters , such as radius and density , to be indirectly estimated .. Please generate the next two sentences of the article

these physical parameters help us to understand the processes by which binary stars form @xcite . in particular , the separation and mass of a binary system tell us about the amount of angular momentum in the system . because it is a conserved quantity , binaries with measured angular momentum

Suppose that you have an abstract for a scientific paper: the time evolution of a large - amplitude electromagnetic ( em ) wave injected vertically into the overhead ionosphere is studied numerically . the em wave has a carrier frequency of 5 mhz and is modulated as a gaussian pulse with a width of approximately 0.1 milliseconds and a vacuum amplitude of 1.5 v / m at 50 km . this is a fair representation of a modulated radio wave transmitted from a typical high - power hf broadcast station on the ground . the pulse is propagated through the neutral atmosphere to the critical points of the ionosphere , where the l - o and r - x modes are reflected , and back to the neutral atmosphere . we observe mode conversion of the l - o mode to electrostatic waves , as well as harmonic generation at the turning points of both the r - x and l - o modes , where their amplitudes rise to several times the original ones . the study has relevance for ionospheric interaction experiments in combination with ground - based and satellite or rocket observations . . And you have already written the first three sentences of the full article: pulsed high - frequency ( hf ) electromagnetic ( em ) waves from transmitters on the ground are regularly used for sounding the density profile and drift velocity of the overehead ionosphere [ _ hunsucker _ , 1991 ; _ reinisch et al . _ , 1995 , _ reinisch _ , 1996 ] . in 1971 , it was shown theoretically by _ perkins and kaw _ [ 1971 ] that if the injected hf radio beams are strong enough , weak - turbulence parametric instabilities in the ionospheric plasma of the type predicted by _ silin _ [ 1965 ] and _ dubois and goldman _ [ 1965 ] would be excited .. Please generate the next two sentences of the article

ionospheric modification experiments by a high - power hf radio wave at platteville in colorado [ _ utlaut _ , 1970 ] , using ionosonde recordings and photometric measurements of artificial airglow , demonstrated the heating of electrons , the deformation in the traces on ionosonde records , the excitation of spread @xmath0 , etc . , after the hf transmitter was turned on . the triggering of weak - turbulence parametric instabilities in the ionosphere

Suppose that you have an abstract for a scientific paper: the quantum dynamics of two distant h atoms excited by ultrashort and spatially shaped laser pulses is studied by the numerical solution of the non - born - oppenheimer time - dependent schrdinger equation within a three - dimensional ( 3d ) model , including the internuclear distance @xmath0 and the two @xmath1 coordinates of the electrons , @xmath2 and @xmath3 . the two 1d hydrogen atoms , a and b , are assumed to be initially in their ground states with a large ( but otherwise arbitrary ) internuclear separation of @xmath4 a.u . ( 5.29 nm ) . two types of a spatial envelope of a laser field linearly polarized along the @xmath1-axis are considered : ( i ) a broad gaussian envelope , such that atom a is excited by the laser field predominantly , and ( ii ) a narrow envelope , such that practically only atom a is excited by the laser field . with the laser carrier frequency @xmath5 a.u . and the pulse duration @xmath6 fs , in both cases an efficient energy transfer from atom a to atom b has been found . the ionization of atom b achieved mostly after the end of the laser pulse is close to or even higher than that of atom a. it is shown that with a narrow spatial envelope of the laser field , the underlying mechanisms of the energy transfer from a to b and the ionization of b are the coulomb attraction of the laser driven electron by the proton of atom b and a short - range coulomb repulsion of the two electrons when their wave functions significantly overlap in the domain of atom b. in the case of a broad gaussian spatial envelope of the laser field , the opposite process also occurs , but with smaller probability : the energy is transferred from the weakly excited atom b to atom a , and the ionization of atom a is also induced by the electron - electron repulsion in the domain of atom a due to a strong overlap of the electronic wave functions . . And you have already written the first three sentences of the full article: the laser driven dynamics of distant quantum systems can depend in general on the spatial and temporal envelope of the applied laser field . for example , at a gas pressure of 1 atm . , the interparticle distance is about 100 a.u . ( 5.29 nm ) .. Please generate the next two sentences of the article

if such a system , e.g. composed of h atoms , is excited by a laser field with the carrier frequency @xmath5 a.u . , corresponding to the ground - state energy of h@xmath7 at a large internuclear distance @xmath0 , the wavelength is @xmath8 a.u .

Suppose that you have an abstract for a scientific paper: in these lectures i discuss the linearization theorem for lie groupoids , and its relation to the various classical linearization theorems for submersions , foliations and group actions . in particular , i explain in some detail the recent metric approach to this problem proposed in @xcite . . And you have already written the first three sentences of the full article: in differential geometry one finds many different normal forms results which share the same flavor . in the last few years we have come to realize that there is more than a shared flavor to many of these results : they are actually instances of the same general result . the result in question is a linearization result for lie groupoids , first conjectured by alan weinstein in @xcite . the first complete proof of the linearization theorem was obtained by nguyen tien zung in @xcite . since then several clarifications and simplifications of the proof , as well as more general versions of this result , were obtained ( see @xcite ) . in these lectures notes we give an overview of the current status of the theory .. Please generate the next two sentences of the article

the point of view followed here , which was greatly influenced by an ongoing collaboration with matias del hoyo @xcite , is that the linearization theorem can be thought of as an ehresmann s theorem for a submersion onto a stack . hence , its proof should follow more or less the same steps as the proof of the classical ehresmann s theorem , which can be reduced to a simple argument using the exponential map of a metric that makes the submersion riemannian .

Suppose that you have an abstract for a scientific paper: we study the mott - insulator transition of bosonic atoms in optical lattices . using perturbation theory , we analyze the deviations from the mean - field gutzwiller ansatz , which become appreciable for intermediate values of the ratio between hopping amplitude and interaction energy . we discuss corrections to number fluctuations , order parameter , and compressibility . in particular , we improve the description of the short - range correlations in the one - particle density matrix . these corrections are important for experimentally observed expansion patterns , both for bulk lattices and in a confining trap potential . . And you have already written the first three sentences of the full article: the mott - hubbard model of interacting bosons on a lattice has been used to describe superfluid mott - insulator transitions in a variety of systems , e.g. , josephson arrays and granular superconductors @xcite . the recent suggestion @xcite to experimentally observe this transition in a system of cold bosonic atoms in an optical lattice and its successful experimental demonstration @xcite has rekindled the interest in the mott - insulator transition and triggered a great deal of theoretical @xcite and experimental @xcite activity . the possibility to directly manipulate and test the many - body behavior of a system of trapped bosonic atoms in an optical lattice @xcite is very attractive .. Please generate the next two sentences of the article

possible applications include the use of a mott state of bosonic atoms in an optical lattice as a starting point to create controlled multiparticle entanglement as an essential ingredient for quantum computation @xcite the mott - insulator quantum phase transition is driven by the interplay of the repulsive interaction of bosons on the same lattice site and the kinetic energy . hence the ratio of the onsite energy and the bandwidth forms the key parameter in the system . in optical lattices , this parameter can be easily controlled and varied by several orders of magnitude , enabling detailed studies of the quantum phase transition .

Suppose that you have an abstract for a scientific paper: the paper is devoted to the spectral analysis of effective preconditioners for linear systems obtained via a finite element approximation to diffusion - dominated convection - diffusion equations . we consider a model setting in which the structured finite element partition is made by equi - lateral triangles . under such assumptions , if the problem is coercive , and the diffusive and convective coefficients are regular enough , then the proposed preconditioned matrix sequences exhibit a strong clustering at unity , the preconditioning matrix sequence and the original matrix sequence are spectrally equivalent , and the eigenvector matrices have a mild conditioning . the obtained results allow to show the optimality of the related preconditioned krylov methods . the interest of such a study relies on the observation that automatic grid generators tend to construct equi - lateral triangles when the mesh is fine enough . numerical tests , both on the model setting and in the non - structured case , show the effectiveness of the proposal and the correctness of the theoretical findings . matrix sequences , clustering , preconditioning , non - hermitian matrix , krylov methods , finite element approximations 65f10 , 65n22 , 15a18 , 15a12 , 47b65 . And you have already written the first three sentences of the full article: the paper is concerned with the spectral and computational analysis of effective preconditioners for linear systems arising from finite element approximations to the elliptic convection - diffusion problem @xmath0 with @xmath1 domain of @xmath2 . we consider a model setting in which the structured finite element partition is made by equi - lateral triangles . the interest of such a partition relies on the observation that automatic grid generators tend to construct equi - lateral triangles when the mesh is fine enough .. Please generate the next two sentences of the article

the analysis is performed having in mind two popular preconditioned krylov methods . more precisely , we analyze the performances of the preconditioned conjugate gradient ( pcg ) method in the case of the diffusion problem and of the preconditioned generalized minimal residual ( pgmres ) in the case of the convection - diffusion problem .

Suppose that you have an abstract for a scientific paper: we revisit the problem of switching off unwanted phase evolution and decoherence in a single two - state quantum system in the light of recent results on random dynamical decoupling methods [ l. viola and e. knill , phys . rev . lett . * 94 * , 060502 ( 2005 ) ] . a systematic comparison with standard cyclic decoupling is effected for a variety of dynamical regimes , including the case of both semiclassical and fully quantum decoherence models . in particular , exact analytical expressions are derived for randomized control of decoherence from a bosonic environment . we investigate quantitatively control protocols based on purely deterministic , purely random , as well as hybrid design , and identify their relative merits and weaknesses at improving system performance . we find that for time - independent systems , hybrid protocols tend to perform better than pure random and may improve over standard asymmetric schemes , whereas random protocols can be considerably more stable against fluctuations in the system parameters . beside shedding light on the physical requirements underlying randomized control , our analysis further demonstrates the potential for explicit control settings where the latter may significantly improve over conventional schemes . . And you have already written the first three sentences of the full article: the design and characterization of strategies for controlling quantum dynamics is vital to a broad spectrum of applications within contemporary physics and engineering . these range from traditional coherent - control settings like high - resolution nuclear @xcite and molecular spectroscopy @xcite , to a variety of tasks motivated by the rapidly growing field of quantum information science @xcite . in particular , the ability to counteract decoherence effects that unavoidably arise in the dynamics of a real - world quantum system coupled to its surrounding environment is a prerequisite for scalable realizations of quantum information processing ( qip ) , as actively pursued through a variety of proposed device technologies @xcite .. Please generate the next two sentences of the article

active decoupling techniques offer a conceptually simple yet powerful control - theoretic setting for quantum - dynamical engineering of both closed - system ( unitary ) and open - system ( non - unitary ) evolutions . inspired by the idea of _ coherent averaging _ of interactions by means of tailored pulse sequences in nuclear magnetic resonance ( nmr ) spectroscopy @xcite , decoupling protocols consist of repetitive sequences of control operations ( typically drawn from a finite repertoire ) , whose net effect is to coherently modify the natural target dynamics to a desired one . in practice , a critical decoupling task is the selective removal of unwanted couplings between subsystems of a fully or partially controllable composite quantum system .

Suppose that you have an abstract for a scientific paper: we study the evolution of the cosmological parameters , namely , the deceleration parameter @xmath0 and the parameter of effective equation of state in a universe containing , besides the ordinary matter and dark energy , a self - interacting ( collisional matter ) , in the generalized @xmath1 theory of gravity , where @xmath2 and @xmath3 are the curvature scalar and the trace of the energy - momentum tensor , respectively . we use the generalized frw equations , the equation of continuity and obtain a differential equation in @xmath4 , and solve it numerically for studying the evolution of the cosmological parameters . two @xmath1 models are considered and the results with collisional matter are compared with the ones of the @xmath5cdm model , and also with the model where there exists only non - collisional matter . the curves show that the models are acceptable because the values found for @xmath6 are consistent with the observational data . . And you have already written the first three sentences of the full article: it is well known nowadays that our current universe is experiencing an accelerated expansion @xcite-@xcite . there are two general ways to explain this accelerated expansion of the universe @xcite-@xcite . the first way is considering that the universe is essentially filled by an exotic fluid with negative pressure , responsible of it acceleration , called the dark energy .. Please generate the next two sentences of the article

the second way is modifying the gravitational action from the general relativity ( gr ) without the need of the dark energy , firstly considered by 1970 @xcite . buchdahl has generalized the einstein equations by substituting the ricci s scalar @xmath2 by an arbitrary function of @xmath2 , named @xmath7 theory of gravity .

Suppose that you have an abstract for a scientific paper: evolutionary algorithms are good general problem solver but suffer from a lack of domain specific knowledge . however , the problem specific knowledge can be added to evolutionary algorithms by hybridizing . interestingly , all the elements of the evolutionary algorithms can be hybridized . in this chapter , the hybridization of the three elements of the evolutionary algorithms is discussed : the objective function , the survivor selection operator and the parameter settings . as an objective function , the existing heuristic function that construct the solution of the problem in traditional way is used . however , this function is embedded into the evolutionary algorithm that serves as a generator of new solutions . in addition , the objective function is improved by local search heuristics . the new neutral selection operator has been developed that is capable to deal with neutral solutions , i.e. solutions that have the different representation but expose the equal values of objective function . the aim of this operator is to directs the evolutionary search into a new undiscovered regions of the search space . to avoid of wrong setting of parameters that control the behavior of the evolutionary algorithm , the self - adaptation is used finally , such hybrid self - adaptive evolutionary algorithm is applied to the two real - world np - hard problems : the graph 3-coloring and the optimization of markers in the clothing industry . extensive experiments shown that these hybridization improves the results of the evolutionary algorithms a lot . furthermore , the impact of the particular hybridizations is analyzed in details as well . _ to cite paper as follows : iztok fister , marjan mernik and janez brest ( 2011 ) . hybridization of evolutionary algorithms , evolutionary algorithms , eisuke kita ( ed . ) , isbn : 978 - 953 - 307 - 171 - 8 , intech , available from : http://www.intechopen.com/books/evolutionary-algorithms/hybridization-of-evolutionary-algorithms_ . And you have already written the first three sentences of the full article: evolutionary algorithms are a type of general problem solvers that can be applied to many difficult optimization problems . because of their generality , these algorithms act similarly like swiss army knife @xcite that is a handy set of tools that can be used to address a variety of tasks . in general , a definite task can be performed better with an associated special tool . however , in the absence of this tool , the swiss army knife may be more suitable as a substitute . for example , to cut a piece of bread the kitchen knife is more suitable , but when traveling the swiss army knife is fine . similarly , when a problem to be solved from a domain where the problem - specific knowledge is absent evolutionary algorithms can be successfully applied .. Please generate the next two sentences of the article

evolutionary algorithms are easy to implement and often provide adequate solutions . an origin of these algorithms is found in the darwian principles of natural selection @xcite . in accordance with these principles

Suppose that you have an abstract for a scientific paper: in this note , we discuss a question posed by t. hoffmann - ostenhof ( see @xcite ) concerning the parity of the number of nodal domains for a non - constant eigenfunction of the laplacian on flat tori . we present two results . we first show that on the torus @xmath0 , a non - constant eigenfunction has an even number of nodal domains . we then consider the torus @xmath1 , with @xmath2 , and construct on it an eigenfunction with three nodal domains . [ [ keywords . ] ] keywords . + + + + + + + + + laplacian , torus , nodal domains . [ [ msc - classification . ] ] msc classification . + + + + + + + + + + + + + + + + + + + 35p99 , 35j05 . . And you have already written the first three sentences of the full article: we consider the non - negative laplace - beltrami operator @xmath3 on the torus @xmath4 , seen as a two - dimensional riemannian manifold , with @xmath5\,$ ] . the eigenvalues of @xmath3 are given by @xmath6 with @xmath7 , and an associated basis of eigenfunctions is given , in the standard coordinates , by @xmath8 @xmath9 @xmath10 @xmath11 to be more precise , the family consisting of all the above functions that are non - zero is an orthogonal basis of @xmath12 . let us note that the eigenspace associated with the eigenvalue @xmath13 is spanned by all the functions in this basis such that the corresponding pair of indices @xmath14 satisfies @xmath15 .. Please generate the next two sentences of the article

if @xmath16 is a rational number , a large eigenvalues can have a very high multiplicity , and an associated eigenfunction can possess a very complex nodal structure ( see for instance @xcite ) . we recall that for any eigenfunction @xmath17 of @xmath18 , we call _ nodal set _ the closed set @xmath19 and _ nodal domain _ a connected component of @xmath20

Suppose that you have an abstract for a scientific paper: the exclusive diffractive production of vector mesons and real photons in @xmath0 collisions has been studied at hera in a wide kinematic range . here we present the most recent experimental results together with a regge - type model . we deduce the pomeranchuk trajectory ( pomeron ) by analyzing the hera data on deeply virtual compton scattering ( dvcs ) , and then discuss its basic properties , namely its apparent hardnessand its non - flatbehavior , different from the claims of some authors . 0.5 cm * exclusive diffraction and pomeron trajectory * * in _ ep _ collisions * 0.3 cm s. fazio@xmath1 and l. jenkovszky@xmath2 @xmath3 _ dipartimento di fisica , universit della calabria _ _ istituto nazionale di fisica nucleare , gruppo collegato di cosenza _ _ i-87036 arcavacata di rende , cosenza , italy _ @xmath4 _ joint institute for nuclear research , 141980 - dubna , moscow region , russia _ @xmath5 _ bogolubov institute for theoretical physics , national academy of sciences of ukraine _ _ kiev-143 , 03680 ukraine _ @xmath6 _ kfki , rmki , budapest , hungary _ 0.1 cm 0.1 cm @xmath7 . And you have already written the first three sentences of the full article: the diffractive scattering is a process where the colliding particles scatter at very small angles and without any color flux in the final state . this involves a propagator carrying the vacuum quantum numbers , called pomeron and described , in the soft regime , within the regge theory . since the first operation period in 1992 , zeus and h1 , the two experiments dedicated to the dis physics at hera , observed that a big amount @xmath8 of lepton - proton dis events had a diffractive origin opening a new area of studies in diffractive production mechanism , providing a hard scale which can be varied over a wide range and therefore it is an ideal testing for qcd models .. Please generate the next two sentences of the article

in particular , the diffractive production of vector mesons ( vms ) and real photons in @xmath0 collisions allows to study the transition from the soft to the hard regime in strong interactions . the hard regime ( high energy and low bjorken-@xmath9 ) is dominated by the exchange of a hard pomeron sensitive to the gluon content and well described by perturbative qcd ( pqcd ) , while in the soft regime ( low-@xmath9 ) the interaction is well described within the regge phenomenology .

Suppose that you have an abstract for a scientific paper: we review a recent asymptotic weak noise approach to the kardar - parisi - zhang equation for the kinetic growth of an interface in higher dimensions . the weak noise approach provides a many body picture of a growing interface in terms of a network of localized growth modes . scaling in 1d is associated with a gapless domain wall mode . the method also provides an independent argument for the existence of an upper critical dimension . . And you have already written the first three sentences of the full article: non equilibrium phenomena are on the agenda in modern statistical physics , soft condensed matter and biophysics . open systems driven far from equilibrium are ubiquitous . a classical case is driven navier stokes turbulence , other cases are driven lattice gases , growing interfaces , growing fractals , etc . unlike equilibrium physics where the boltzmann - gibbs scheme applies , the ensemble is not known in non equilibrium . here. Please generate the next two sentences of the article

the problem is defined in terms of a numerical algorithm , a master equation , or a langevin equation . an interesting class of non equilibrium systems exhibit scale invariance . one example is diffusion limited aggregation ( dla ) driven by the accretion of random walkers yielding a growing scale invariant fractal with dimension @xmath0 in 2d .

Suppose that you have an abstract for a scientific paper: we briefly summarize the current status of perturbative calculations at next - to - next - to - leading - order ( nnlo ) accuracy in the @xmath0 decay rate as well as that of non - perturbative power - corrections . . And you have already written the first three sentences of the full article: corrections to the @xmath0 decay are usually described in the framework of an effective theory , ) we discarded terms proportional to @xmath1 since they give only small contributions to the branching ratio that start at next - to - leading - order ( nlo ) . similar nnlo corrections can therefore be safely neglected . ] @xmath2 here , @xmath3 are renormalization scale dependent effective couplings , the so - called wilson coefficients , which encode the heavy gauge boson and the heavy top quark effects .. Please generate the next two sentences of the article

the @xmath4-quark scale contributions , on the other hand , are seen as matrix elements of flavor changing operators , @xmath5 o_{3,5 } & = ( \bar s_l\gamma_{3,5 } b_l){\sum}_q(\bar q\gamma_{3,5}^\prime q)\ , , & o_{4,6 } & = ( \bar s_l\gamma_{3,5 } t^a b_l){\sum}_q(\bar q\gamma_{3,5}^\prime t^a q)\,,\nonumber\\[1 mm ] o_7 & = \frac{\alpha_{\rm em}}{4\pi}\,m_b(\bar s_l\sigma^{\mu\nu}b_r)f_{\mu\nu}\ , , & o_8 & = \frac{\alpha_{s}}{4\pi}\,m_b(\bar s_l\sigma^{\mu\nu } t^a b_r)g^a_{\mu\nu}\,,\end{aligned}\ ] ] where @xmath6 , @xmath7 , @xmath8 and @xmath9 . using ( [ eq::lagrangian ] ) , the differential decay rate for @xmath0 can be written as follows , @xmath10 in the equation displayed above , @xmath11 denotes the momentum of the photon and the @xmath12 , which describe the hadronic dynamics , are given by the imaginary part of forward scattering amplitudes , @xmath13 since the mass of the @xmath4-quark is much larger than the binding energy of the @xmath14-meson , which is of the order of @xmath15 , we can perform an operator product expansion ( ope ) of the time ordered products . doing so , one finds that the leading term is the partonic decay rate which gives the dominant contribution , while the non - leading terms , the so - called power - corrections , are suppressed by powers of @xmath16 and give non - vanishing contributions starting from @xmath17 . ) and its ope hold only for @xmath18 . in all other cases

Suppose that you have an abstract for a scientific paper: the full set of high - energy spectroscopy measurements including x - ray photoelectron valence band spectra and soft x - ray emission valence band spectra of both components of fesi ( fe @xmath0 , fe @xmath1 , si @xmath2 and si @xmath3 ) are performed and compared with the results of _ ab - initio _ band structure calculations using the linearized muffin - tin orbital method and linearized augmented plane wave method . . And you have already written the first three sentences of the full article: fesi is a non - magnetic @xcite , narrow - gap semiconductor @xcite at low temperatures . its magnetic susceptibility @xmath4 increases with temperature and passes through a maximum at @xmath5 k @xcite . fesi becomes metallic above 300 k@xcite .. Please generate the next two sentences of the article

the substitution of co for fe ( about 10% co ) yields a magnet with a helical spin order @xcite . local density functional@xcite band structure calculations @xcite give the correct value of the semiconducting gap ( about 0.1 ev ) , but can not explain the large magnitude of @xmath4 . according to infrared and optical measurements @xcite , the gap of 50 mev is gradually filled with increasing temperature , with new spectral weight which can not be explained within the conventional band structure picture . in connection with a temperature - induced local moment ,

Suppose that you have an abstract for a scientific paper: we consider least energy solutions to the nonlinear equation @xmath0 posed on a class of riemannian models @xmath1 of dimension @xmath2 which include the classical hyperbolic space @xmath3 as well as manifolds with unbounded sectional geometry . partial symmetry and existence of least energy solutions is proved for quite general nonlinearities @xmath4 , where @xmath5 denotes the geodesic distance from the pole of @xmath6 . . And you have already written the first three sentences of the full article: let @xmath1 be a @xmath7-dimensional riemannian model ( @xmath8 ) , namely a manifold admitting a pole @xmath9 and whose metric is given , in spherical coordinates around @xmath9 , by @xmath10 where @xmath11 denotes the canonical metric on the unit sphere @xmath12 and * @xmath13 is a @xmath14 nonnegative function on @xmath15 , positive on @xmath16 such that @xmath17 and @xmath18 for all @xmath19 . these conditions on @xmath13 ensure that the manifold is smooth and the metric at the pole @xmath9 is given by the euclidean metric ( * ? ? ? * chapter 1 , 3.4 ) .. Please generate the next two sentences of the article

then , by construction , @xmath20 is the geodesic distance between a point @xmath21 whose coordinates are @xmath22 and @xmath9 . let @xmath23 denote the laplace - beltrami operator on @xmath6 .

Suppose that you have an abstract for a scientific paper: by definition , transverse intersections are stable under infinitesimal perturbations . using persistent homology , we extend this notion to a measure . given a space of perturbations , we assign to each homology class of the intersection its robustness , the magnitude of a perturbation in this space necessary to kill it , and prove that robustness is stable . among the applications of this result is a stable notion of robustness for fixed points of continuous mappings and a statement of stability for contours of smooth mappings . . And you have already written the first three sentences of the full article: the main new concept in this paper is a quantification of the classically differential notion of transversality . this is achieved by extending persistence from filtrations of homology groups to zigzag modules of well groups . [ [ motivation . ] ] motivation .. Please generate the next two sentences of the article

+ + + + + + + + + + + in hind - sight , we place the starting point for the work described in this paper at the difference between qualitative and quantitative statements and their relevance in the sciences ; see eg . the discussion in thom s book ( * ? ? ? * chapters 1.3 and 13.8 ) .

Suppose that you have an abstract for a scientific paper: we study the degree to which quantum entanglement survives when a three - qubit entangled state is copied by using local and non - local processes , respectively , and investigate iterating quantum copying for the three - qubit system . there may exist inter - three - qubit entanglement and inter - two - qubit entanglement for the three - qubit system . we show that both local and non - local copying processes degrade quantum entanglement in the three - particle system due to a residual correlation between the copied output and the copying machine . we also show that the inter - two - qubit entanglement is preserved better than the inter - three - qubit entanglement in the local cloning process . we find that non - local cloning is much more efficient than the local copying for broadcasting entanglement , and output state via non - local cloning exhibits the fidelity better than local cloning . . And you have already written the first three sentences of the full article: the most fundamental difference between classical and quantum information is that while classical information can be copied perfectly , quantum information can not . in particular , it follows from the no - cloning theorem @xcite that one can not create a perfect duplicate of an arbitrary qubit . nevertheless , buzek and hillery and other authors @xcite have shown that imperfect copies can be made by a universal quantum cloning machine ( uqcm ) , the outputs of which are identical .. Please generate the next two sentences of the article

the price which must be paid is that there is a difference between the original input and the copies , because of residual entanglement between the machine and copies . however , not only similarity is lost during the cloning process .

Suppose that you have an abstract for a scientific paper: as yet , there is no underlying fundamental theory for the transplanckian regime . there is a need to address the issue of how the observables in our present universe are affected by processes that may have occurred at superplanckian energies ( referred to as the _ transplanckian regime _ ) . specifically , we focus on the impact the transplanckian regime has on two observables , namely : dark energy and the cmbr spectrum . we model the transplanckian regime by introducing a 1-parameter family of smooth non - linear dispersion relations which modify the frequencies at very short distances . a particular feature of the family of dispersion functions chosen is the production of ultralow frequencies at very high momenta @xmath0 ( for @xmath1 ) . we name the range of the ultralow energy modes ( of very short distances ) that have frequencies equal or less than the current hubble rate @xmath2 as the _ tail _ modes . these modes are still frozen today due to the expansion of the universe . we calculate their energy today and show that the @xmath3 provides a strong candidate for the _ dark energy _ of the universe . during inflation , their energy is about 122 - 123 orders of magnitude smaller than the total energy , for any random value of the free parameter in the family of dispersion relations . for this family of dispersions , we present the exact solutions and show that : the cmbr spectrum is that of a ( nearly ) black body , and that the adiabatic vacuum is the only choice for the initial conditions . 6.0 in 9.0 in # 1#2#3 # 1#2#3 # 1#2#3 # 1#2#3 # 1#2#3 # 1#2#3 # 1#2#3 hep - ph/0101210 + sns - ph/01 - 01 + + laura mersini , mar bastero - gil and panagiota kanti + + _ scuola normale superiore and infn , piazza dei cavalieri 7 , + i-56126 pisa , italy _ + [ cols= " < " , ] . And you have already written the first three sentences of the full article: there is still no fundamental physical theory of the very early universe which addresses issues that arise from the regime of transplanckian physics . one of these issues relates to the origin of the cosmological perturbation spectrum . in an expanding universe , the physical momentum gets blue - shifted back in time , therefore the observed low values of the momentum today that contribute to the cmbr spectrum may have originated from values larger than the planck mass @xmath4 in the early universe .. Please generate the next two sentences of the article

this is similar to the problems that arise in trying to explain the origin of hawking radiation in black hole physics . in a series of papers @xcite , it was demonstrated that the hawking radiation remains unaffected by modifications of the ultra high energy regime , expressed through the modification of the usual linear dispersion relation at energies larger than a certain ultraviolet scale @xmath5 . following a similar procedure , in the case of an expanding friedmann - lemaitre - robertson - walker ( flrw ) spacetime , martin and brandenberger in ref .

Suppose that you have an abstract for a scientific paper: we study the magnetic soliton dynamics of spinor bose - einstein condensates in an optical lattice which results in an effective hamiltonian of anisotropic pseudospin chain . a modified landau - lifshitz equation is derived and exact magnetic soliton solutions are obtained analytically . our results show that the time - oscillation of the soliton size can be controlled in practical experiment by adjusting of * * * * the light - induced dipole - dipole interaction . moreover , the elastic collision of two solitons is investigated . . And you have already written the first three sentences of the full article: recently , spinor bose - einstein condensates ( becs ) trapped in optical potentials have received much attention in both experimental stenger , anderson , liu and theoretical studies @xcite . spinor becs have internal degrees of freedom due to the hyperfine spin of the atoms which liberate a rich variety of phenomena such as spin domains @xcite and textures @xcite . when the potential valley is so deep that the individual sites are mutually independent , spinor becs at each lattice site behave like spin magnets and can interact with each other through both the light - induced and the static , magnetic dipole - dipole interactions .. Please generate the next two sentences of the article

these site - to - site dipolar interactions can cause the ferromagnetic phase transition @xcite leading to a macroscopic magnetization of the condensate array and the spin - wave like excitation @xcite analogous to the spin - wave in a ferromagnetic spin chain . for the real spin chain , the site - to - site interaction is caused mainly by the exchange interaction , while the dipole - dipole interaction is negligibly small .

Suppose that you have an abstract for a scientific paper: we study rare events in systems of diffusive fields driven out of equilibrium by the boundaries . we present a numerical technique and use it to calculate the probabilities of rare events in one and two dimensions . using this technique , we show that the probability density of a slowly varying configuration can be captured with a small number of long wave - length modes . for a configuration which varies rapidly in space this description can be complemented by a local equilibrium assumption . in many cases the typical size of fluctuations in a physical system with @xmath0 degrees of freedom is of order @xmath1 . larger fluctuations are rare , and their probability scales as @xmath2 \sim\exp\left ( -n\phi\left [ \rho\right ] \right ) \,$ ] , where @xmath3 is an intensive function of the state @xmath4 . the function @xmath5 $ ] is known as the _ large - deviation _ _ function _ ( ldf ) and is of fundamental interest in statistical mechanics . in equilibrium systems , @xmath3 is equal to the free - energy density . away from equilibrium , a simple expression for @xmath3 is in general not known , and it may be affected by details of the system s dynamics . besides its fundamental interest for non - equilibrium physics , the function @xmath3 is important in various applications , e.g. for calculating escape rates from metastable states , with applications ranging from chemistry and population dynamics to cosmology @xcite . in a non - equilibrium steady - state , to compute the probability of a rare - event , one must calculate the dynamics leading up to that event @xcite . this is in general a difficult task , even more so for spatially extended systems , where only a handful of analytical solutions exist @xcite . if a general understanding is to emerge , additional methods beyond exact solutions need to be considered . indeed , recent years have seen a considerable effort to develop numerical techniques to calculate the ldf in a variety of systems @xcite . in this.... And you have already written the first three sentences of the full article: the action evaluation , including the lagrange multipliers , is implemented directly in the discrete setting , which gives discrete variants of eq . ( [ eq.hamilton_rho_eom ] ) , along with the boundary conditions . in the numerical implementation , time and space are discretized , and @xmath4 is kept at points @xmath145 in 1d , and @xmath146 in 2d .. Please generate the next two sentences of the article

we start by describing the method in 2d , and then discuss the simplifications which occur in 1d . the action , eq . ( [ eq : action ] ) , is discretized as @xmath147 where @xmath148 is the value of @xmath37 associated with the time interval @xmath149 $ ] .

Suppose that you have an abstract for a scientific paper: the advent of wide - area multicolour synoptic sky surveys is leading to data sets unprecedented in size , complexity and data throughput . vo technology offers a way to exploit these to the full but requires changes in design philosophy . the palomar - quest survey is a major new survey being undertaken by caltech , yale , jpl and indiana university to repeatedly observe @xmath0 of the sky ( @xmath1 sq . deg . between @xmath2 ) in seven passbands . utilising the 48-inch oschin schmidt telescope at the palomar observatory with the 112-ccd quest camera covering the full 4@xmath3 x 4@xmath3 field of view , it will generate @xmath4 tb of data per month . in this paper , we review the design of quest as a vo resource , a federated data set and an exemplar of vo standards . . And you have already written the first three sentences of the full article: the new availability of wide - field images from schmidt telescopes in the 1940 s meant that astronomers no longer had to make educated guesses about where to look to find new and interesting phenomena but were now spoilt for choice . the advent of synoptic surveys presents more extreme opportunities ; as an illustration , consider the sdss which over the course of 5 years represents a factor of a million increase in information over previous surveys ; however , the ( large sky synoptic telescope , tyson ( 2002 ) ) will amass a sdss every 3 nights . although overviews of synoptic surveys are riddled with cliches concerning undiscovered countries and uncharted waters , the exploration of the temporal domain results in data sets that are not just more voluminous than before , but far richer and more complex ( paczynski 2001 ; djorgovski et al . this presents challenges to all aspects of astronomy : data gathering , distribution , reduction , analysis , storage , archiving , dissemination and mining .. Please generate the next two sentences of the article

vo technologies are being designed precisely to meet these types of challenges , but to use them requires changes in survey design philosophies . the is a major new survey being undertaken by caltech , yale , jpl and indiana university employing the world s largest astronomical camera and the recently refurbished oschin schmidt telescope at palomar to observe a third of the sky ( @xmath1 sq . deg . between @xmath2 ) a minimum of 8 times in 7 passbands to nominally twice the depth of sdss .

Suppose that you have an abstract for a scientific paper: using the perturbative method for the simulation of charmed particles , the dynamical origin of charm quark elliptic flow is studied in the framework of a multi - phase transport ( ampt ) model . besides the expected ordering relative to that of light quarks according to quark masses , charm quark elliptic flow is seen to be sensitive to the parton scattering cross section . to describe the observed large elliptic flow of electrons from the decay of charmed mesons , a charm quark elastic scattering cross section much larger than that estimated from the perturbative qcd is required . . And you have already written the first three sentences of the full article: because of their large masses , charm quarks are produced very early and propagate through the quark - gluon plasma formed in relativistic heavy ion collisions . any modifications of charm quark spectrum thus carry information on the properties of the quark - gluon plasma . although charmed hadrons are at present not directly observable in central nucleus - nucleus collisions at the relativistic heavy ion collider ( rhic ) , experimental data on the transverse momentum spectrum of electrons from their decays have already provided useful information on the interaction of charm quarks in the quark - gluon plasma .. Please generate the next two sentences of the article

for example , the transverse momentum spectrum of these electrons is found to be insensitive to the charm final - state interactions as results from both the pythia model and the blastwave hydrodynamic model are consistent with the experimental data @xcite . on the other hand , the large elliptic flow of these electrons is consistent with the prediction of the coalescence model @xcite which assumes that charm and light quarks are in thermal equilibrium and have same elliptic flow . in the present talk

Suppose that you have an abstract for a scientific paper: weakly interacting massive particles ( wimps ) are one of the leading candidates for dark matter . currently , the most promising method to detect many different wimp candidates is the direct detection of the recoil energy deposited in a low background laboratory detector due to elastic wimp nucleus scattering . so far the usual procedure has been to predict the event rate of direct detection of wimps based on some model(s ) of the galactic halo . the aim of our work is to invert this process . that is , we study what future direct detection experiment can teach us about the wimp halo . as the first step we consider a time averaged recoil spectrum , assuming that no directional information exists . we develop a method to construct the ( time averaged ) one dimensional velocity distribution function from this spectrum . moments of this function , such as the mean velocity and velocity dispersion of wimps , can also be obtained directly from the recoil spectrum . the only input needed in addition to a measured recoil spectrum is the mass of the wimp ; no information about the scattering cross section or wimp density is required . march 2007 * reconstructing the velocity distribution of wimps + from direct dark matter detection data * + and chung - lin shan + . And you have already written the first three sentences of the full article: the first indication of the existence of dark matter has already been found in the 1930s @xcite . by now astrophysicists have strong evidence @xcite-@xcite to believe that a large fraction ( more than 80% ) of the matter in the universe is dark ( i.e. , interacts at most very weakly with electromagnetic radiation ) . the dominant component of this cosmological dark matter must be due to some yet to be discovered , non baryonic particles . weakly interacting massive particles ( wimps ) @xmath0 are one of the leading candidates for dark matter .. Please generate the next two sentences of the article

wimps are stable particles which arise in several extensions of the standard model of electroweak interactions . typically they are presumed to have masses between 10 gev and a few tev and interact with ordinary matter only weakly ( for reviews , see @xcite ) . currently , the most promising method to detect many different wimp candidates is the direct detection of the recoil energy deposited in a low background laboratory detector by elastic scattering of ambient wimps on the nuclei in a detector @xcite-@xcite .

Suppose that you have an abstract for a scientific paper: over the course of eleven months we determined the position of mars on 45 occasions using a handheld cross staff and two to five bright reference stars of known right ascension and declination on each occasion . on average the observed positions are within 12 of the true positions . given that we took data prior to the start of retrograde motion and well past the end of retrograde motion , we can easily derive the date of opposition to the sun . we were able to derive the date of perihelion , the orbital eccentricity , and the semi - major axis size of mars orbit . we obtain a value of the eccentricity of 0.086 @xmath0 0.010 , which is to be compared to the modern value of 0.0934 . values as low as 0.053 or as high as 0.123 can be rejected at a high confidence level . a simple dataset can be obtained with cardboard and a ruler that demonstrates the elliptical shape of mars orbit . = 1 . And you have already written the first three sentences of the full article: the fundamental paradigm of solar system astronomy prior to the time of copernicus was that the earth was at the center of the solar system . also , celestial bodies were assumed to move along perfect circles . this led to the system of deferents and epicycles .. Please generate the next two sentences of the article

one prime motivation for the use of epicycles was to account for retrograde motion . copernicus great book _ on the revolutions of the heavenly spheres _

Suppose that you have an abstract for a scientific paper: for gravity coupled to @xmath0 scalar fields , with arbitrary potential @xmath1 , it is shown that all flat ( homogeneous and isotropic ) cosmologies correspond to geodesics in an @xmath2-dimensional ` augmented ' target space of lorentzian signature @xmath3 , timelike if @xmath4 , null if @xmath5 and spacelike if @xmath6 . accelerating cosmologies correspond to timelike geodesics that lie within an ` acceleration subcone ' of the ` lightcone ' . non - flat ( @xmath7 ) cosmologies are shown to evolve as projections of geodesic motion in a space of dimension @xmath8 , of signature @xmath9 for @xmath10 and signature @xmath11 for @xmath12 . this formalism is illustrated by cosmological solutions of models with an exponential potential , which are comprehensively analysed ; the late - time behaviour for other potentials of current interest is deduced by comparison . . And you have already written the first three sentences of the full article: cosmological models with scalar field matter have been much studied in the context of inflation and , more recently , in the context of the late - time acceleration that is indicated by current astronomical observations ( see @xcite for a recent review ) . one theoretical motivation for these studies is that scalar fields arise naturally from the compactification of higher - dimensional theories , such as string or m - theory . however , the type of scalar field potential obtained in these compactifications is sufficiently restrictive that until recently it was considered to be difficult to get accelerating cosmologies in this way , although the existence of an accelerating phase in a hyperbolic ( @xmath13 ) universe obtained by compactification had been noted @xcite , and non - perturbative effects in m - theory have since been shown to allow unstable de sitter vacua @xcite . in an earlier paper , we pointed out that compactification on a compact hyperbolic manifold with a time - dependent volume modulus naturally leads to a flat ( @xmath14 ) expanding universe that undergoes a transient period of accelerating expansion @xcite .. Please generate the next two sentences of the article

numerous subsequent studies have shown that such cosmological solutions are typical to all compactifications that involve compact hyperbolic spaces or non - vanishing @xmath15-form field strengths ( flux ) @xcite , and this was additionally confirmed in a systematic study @xcite . furthermore , the transient acceleration in these models is easily understood @xcite in terms of the positive scalar field potential that both hyperbolic and flux compactifications produce in the effective , lower - dimensional , action .

Suppose that you have an abstract for a scientific paper: we report a late m - type , common proper motion companion to a nearby young visual binary hip 115147 ( v368 cep ) , separated by 963 arcseconds from the primary k0 dwarf . this optically dim star has been identified as a candidate high proper motion , nearby dwarf lspm j2322 + 7847 by lpine in 2005 . the wide companion is one of the latest post - t tauri low mass stars found within 20 pc . we obtain a trigonometric parallax of @xmath0 mas , in good agreement with the hipparcos parallax of the primary star ( @xmath1 mas ) . our @xmath2 photometric data and near - infrared data from 2mass are consistent with lspm j2322 + 7847 being brighter by 1 magnitude in @xmath3 than field m dwarfs at @xmath4 , which indicates its pre - main sequence status . we conclude that the most likely age of the primary hip 115147 and its 11-arcsecond companion hip 115147b is 20 - 50 myr . the primary appears to be older than its close analog pz tel ( age 12 - 20 myr ) and members of the twa association ( 7 myr ) . [ firstpage ] . And you have already written the first three sentences of the full article: in the course of an extensive search for very wide , common proper motion companions to nearby hipparcos stars from the nomad catalog @xcite , we came across an optically faint and red star at an angular separation of @xmath5 , position angle @xmath6 from the active and rapidly rotating g9v star hip 115147 ( bd + 78 826 , hd 220140 , v368 cep ) . this faint star was subsequently identified with lspm j2322 + 7847 , a candidate nearby low - mass dwarf detected by @xcite from the lspm - north catalog @xcite . the original identification of this star as one with significant proper motion traces to luyten ( 1967 ) where it was reported as a magnitude 17 object with @xmath7 mas yr@xmath8 at a position angle of @xmath9 and assigned the name lp12 - 90 . in the present paper. Please generate the next two sentences of the article

we present new @xmath2 photometry of hip 115147 , its known visual companion hip 115147b and lspm j2322 + 7847 , and obtain preliminary trigonometric parallax astrometry for the latter companion . then we discuss the possible young age and origin of this interesting triple system .

Suppose that you have an abstract for a scientific paper: the uniaxial stress dependence of the band structure and the exciton - polariton transitions in wurtzite zno is thoroughly studied using modern first - principles calculations based on the hse+@xmath0 approach , @xmath1 modeling using the deformation potential framework , and polarized photoluminescence measurements . the ordering of the valence bands [ a(@xmath2 ) , b(@xmath3 ) , c(@xmath2 ) ] is found to be robust even for high uniaxial and biaxial strains . theoretical results for the uniaxial pressure coefficients and splitting rates of the a , b , and c valence bands and their optical transitions are obtained including the effects of the spin - orbit interaction . the excitonic deformation potentials are derived and the stress rates for hydrostatic pressure are determined based on the results for uniaxial and biaxial stress . in addition , the theory for the stress dependence of the exchange interaction and longitudinal - transversal splitting of the exciton - polaritons is developed using the basic exciton functions of the quasi - cubic approximation and taking the interaction between all exciton states into account . it is shown that the consideration of these effects is crucial for an accurate description of the stress dependence of the optical spectra in zno . the theoretical results are compared to polarized photoluminescence measurements of different zno substrates as function of uniaxial pressure and experimental values reported in the literature demonstrating an excellent agreement with the computed pressure coefficients . + doi : 10.1103/physrevb.88.235210 . And you have already written the first three sentences of the full article: the electronic band structure and the related exciton - polariton transitions in wurtzite semiconductors were investigated in countless experimental and theoretical studies over the past five to six decades . indeed for zno important contributions in the field were already published in the early 1960s @xcite . nevertheless , fundamental properties such as the ordering of the valence bands ( vbs ) and the influence of stress on the exciton - polariton transitions remain controversial to the present day . magnetic fields and external pressure constitute powerful tools to obtain detailed information about electronic band structures and optical transitions by studying the exciton - polariton fine structure .. Please generate the next two sentences of the article

in addition , in recent years , significant advances in computational power and theoretical algorithms have enabled electronic - structure calculations , including quasiparticle ( qp ) effects and electron - hole interaction which reproduce experimental results to a high degree of precision . consequently , it is now possible to conduct complex calculations taking into account , for instance , the influence of stress on the electronic band structure and the exciton - polariton transitions in direct comparison to experimental results .

Suppose that you have an abstract for a scientific paper: fix an integer @xmath0 and let @xmath1 be the pseudo - process driven by the high - order heat - type equation @xmath2 . the denomination `` pseudo - process '' means that @xmath3 is related to a signed measure ( which is not a probability measure ) with total mass equal to 1 . in this survey , we present several explicit results and discuss some problems concerning the pseudo - distributions of various functionals of the pseudo - process @xmath3 : the first or last overshooting times of a single barrier @xmath4 or a double barrier @xmath5 by @xmath3 ; the sojourn times of @xmath3 in the intervals @xmath6 and @xmath7 $ ] up to a fixed time ; the maximum or minimum of @xmath3 up to a fixed time . * keywords . pseudo - process ; pseudo - distribution ; first hitting or overshooting time ; sojourn time ; up - to - date maximum . * . And you have already written the first three sentences of the full article: consider the heat - type equation @xmath8 of order @xmath0 where @xmath9 if @xmath10 is even and @xmath11 if @xmath10 is odd . let us introduce the corresponding kernel @xmath12 which is characterized by @xmath13 this kernel defines a pseudo - process @xmath14 driven by a signed measure with total mass equal to 1 ( which is not a probability measure ) according as the usual markov rules : we set for @xmath15 , @xmath16 and @xmath17 , @xmath18 and @xmath19 since we are dealing with a signed measure , it seems impossible to extend the definition of the pseudo - process over all the positive times . we can find in the literature two possible ad - hoc constructions : one over the set of times of the form @xmath20 , @xmath21 ( depending on a fixed time @xmath22 , see @xcite and @xcite for pioneering works related to this construction ) , the other one over the set of dyadic times @xmath23 , @xmath21 .. Please generate the next two sentences of the article

( which do not depend on any particular time , see @xcite for this last construction ) . for @xmath24 , this is the most well - known brownian motion and for @xmath25 , @xmath14 is the so - called biharmonic pseudo - process . for the pseudo - process @xmath14 started at a point @xmath26 , we introduce : * the first overshooting times of a one - sided barrier @xmath4 ( or , equivalently , the first hitting time of the half - line @xmath6 ) or a two - sided barrier @xmath5 ( with the convention @xmath27 ) : @xmath28\}\mbox { for $ x\in[a , b]$};\end{aligned}\ ] ] * the last overshooting times of such barriers before a fixed time @xmath22 ( with the convention @xmath29 ) : @xmath30:x(s)\ge a\},\quad \sigma_{ab}(t ) = \sup\{s\in[0,t]:x(t)\notin ( a , b)\};\end{aligned}\ ] ] * the sojourn times in the intervals @xmath6 and @xmath7 $ ] up to a fixed time @xmath22 : @xmath31:x(s)\ge a\},\quad t_{ab}(t ) = \mathrm{measure}\{s\in[0,t]:x(s)\in[a , b]\};\ ] ] * the maximum up to time @xmath22 : @xmath32 in the foregoing rough definitions , the pseudo - distribution of the quantity @xmath33 for instance is to be understood as the limit of @xmath34 when @xmath35 .

Suppose that you have an abstract for a scientific paper: the electronic structure of the doped manganites pr@xmath0ca@xmath1mno@xmath2 was calculated by the lsda+u method which takes into account the local coulomb interaction between d - electrons of transition metal ions . in contrast to the standard local spin density approximation ( lsda ) no jahn - teller lattice distortions are needed to reproduce the experimentally observed orbital ordering in the undoped prmno@xmath2 . the correct ground state : a charge and orbital ordered antiferromagnetic insulator , was obtained for pr@xmath3ca@xmath3mno@xmath2 . the results are in good agreement with the neutron diffraction data . . And you have already written the first three sentences of the full article: the doped rare earth manganites @xmath4mno@xmath2 ( @xmath5 is a rare earth such as la and @xmath6 is a divalent element such as sr or ca ) due to their peculiar correlation between magnetism and conductivity have been extensively studied during 1950s and 60s @xcite . the most throughly investigated was the la@xmath0sr@xmath1mno@xmath2 system . undoped ( @xmath7=0 ) , lamno@xmath2 is an antiferromagnetic insulator . upon doping with sr ,. Please generate the next two sentences of the article

this perovskite oxide becomes a ferromagnetic metal ; the connection between metallicity and ferromagnetism was well explained by the double exchange hopping mechanism @xcite . the discovery of colossal magnetoresistance phenomena in samples with sr dopant densities in the 0.2@xmath80.4 regime @xcite brought a revival of the interest to these sytems .

Suppose that you have an abstract for a scientific paper: we characterize the completeness of point source lists from _ spitzer space telescope _ surveys in the four infrared array camera ( irac ) bandpasses , emphasizing the galactic legacy infrared mid - plane survey extraordinaire ( glimpse ) programs ( glimpse i , ii , 3d , 360 ; deep glimpse ) and their resulting point source catalogs and archives . the analysis separately addresses effects of incompleteness resulting from high diffuse background emission and incompleteness resulting from point source confusion ( i.e. , crowding ) . an artificial star addition and extraction analysis demonstrates that completeness is strongly dependent on local background brightness and structure , with high - surface - brightness regions suffering up to five magnitudes of reduced sensitivity to point sources . this effect is most pronounced at the irac 5.8 and 8.0 @xmath0 m bands where uv - excited pah emission produces bright , complex structures ( photodissociation regions ; pdrs ) . with regard to diffuse background effects , we provide the completeness as a function of stellar magnitude and diffuse background level in graphical and tabular formats . these data are suitable for estimating completeness in the low - source - density limit in any of the four irac bands in glimpse catalogs and archives and some other @xmath1 irac programs that employ similar observational strategies and are processed by the glimpse pipeline . by performing the same analysis on smoothed images we show that the point source incompleteness is primarily a consequence of _ structure _ in the diffuse background emission rather than photon noise . with regard to source confusion in the high - source - density regions of the galactic plane , we provide figures illustrating the 90% completeness levels as a function of point source density at each band . we caution that completeness of the glimpse 360/deep glimpse catalogs is suppressed relative to the corresponding archives as a consequence of rejecting stars that lie in the psf wings.... And you have already written the first three sentences of the full article: the _ spitzer space telescope _ @xcite has conducted numerous wide - area surveys , yielding a rich legacy of image data and point source catalogs that have become heavily used commodities . in terms of sky coverage , the largest of these are the galactic legacy infrared mid - plane survey extraordinaire programs ( glimpse , glimpse ii , glimpse 3d ; * ? ? ?. Please generate the next two sentences of the article

* ; * ? ? ? * ) covering almost 400 square degrees of the milky way plane in all four mid - infrared bands with the infrared array camera ( irac ; * ? ? ?

Suppose that you have an abstract for a scientific paper: we discuss the effect of the supersymmetry breaking on the mass varying neutrinos(mavans ) scenario . especially , the effect mediated by the gravitational interaction between the hidden sector and the dark energy sector is studied . a model including a chiral superfield in the dark sector and the right handed neutrino superfield is proposed . evolutions of the neutrino mass and the equation of state parameter are presented in the model . it is remarked that only the mass of a sterile neutrino is variable in the case of the vanishing mixing between the left - handed and a sterile neutrino on cosmological time scale . the finite mixing makes the mass of the left - handed neutrino variable . . And you have already written the first three sentences of the full article: in recent years , many cosmological observations have provided the strong evidence that the universe is flat and its energy density is dominated by the dark energy component whose negative pressure causes the cosmic expansion to accelerate @xcite@xmath0@xcite . in order to clarify the origin of the dark energy , one has tried to understand the connection of the dark energy with particle physics . in a dynamical model proposed by fardon , nelson and weiner ( mavans ) , relic neutrinos could form a negative pressure fluid and cause the cosmic acceleration @xcite . in this model , an unknown scalar field which is called `` acceleron '' is introduced and neutrinos are assumed to interact through a new scalar force .. Please generate the next two sentences of the article

the acceleron sits at the instantaneous minimum of its potential , and the cosmic expansion only modulates this minimum through changes in the neutrino density . therefore , the neutrino mass is given by the acceleron , in other words , it depends on its number density and changes with the evolution of the universe .

Suppose that you have an abstract for a scientific paper: the constrained @xmath0 regularization plays an important role in sparse reconstruction . a widely used approach for solving this problem is the penalty method , of which the least square penalty problem is a special case . however , the connections between global minimizers of the constrained @xmath0 problem and its penalty problem have never been studied in a systematic way . this work provides a comprehensive investigation on optimal solutions of these two problems and their connections . we give detailed descriptions of optimal solutions of the two problems , including existence , stability with respect to the parameter , cardinality and strictness . in particular , we find that the optimal solution set of the penalty problem is piecewise constant with respect to the penalty parameter . then we analyze in - depth the relationship between optimal solutions of the two problems . it is shown that , in the noisy case the least square penalty problem probably has no common optimal solutions with the constrained @xmath0 problem for any penalty parameter . under a mild condition on the penalty function , we establish that the penalty problem has the same optimal solution set as the constrained @xmath0 problem when the penalty parameter is sufficiently large . based on the conditions , we further propose exact penalty problems for the constrained @xmath0 problem . finally , we present a numerical example to illustrate our main theoretical results . optimal solutions , constrained @xmath0 regularization , penalty methods , stability . And you have already written the first three sentences of the full article: signal reconstruction is usually formulated as a linear inverse problem @xmath1 where @xmath2 is the true signal , @xmath3 is an @xmath4 real matrix , @xmath5 is the observed data and @xmath6 represents the random noise . over the last decade , sparse reconstruction has received great attentions @xcite . in general , the task of sparse reconstruction is to find a sparse @xmath7 from .. Please generate the next two sentences of the article

obviously , the most natural measure of sparsity is the @xmath0-norm , defined at @xmath2 as @xmath8 where @xmath9 stands for the cardinality of the set @xmath10 and @xmath11 denotes the support of @xmath7 , that is @xmath12 . when the noise level of @xmath13 is known , we consider the following constrained @xmath0 regularization problem @xmath14 where @xmath15 denotes the @xmath16-norm , and @xmath17 is the noise level . specially , in the noiseless case , i.e. , when @xmath18 , problem reduces to seeking for the sparsest solutions from a linear system as follows @xmath19 finding a global minimizer of problem is known to be combinational and np - hard in general @xcite as it involves the @xmath0-norm . the number of papers dealing with the @xmath0-norm is large and several types of numerical algorithms have been adopted to approximately solve the problem . in this paper , we mainly focus on the penalty methods . before making a further discussion on the penalty methods , we briefly review other two types of approaches , greedy pursuit methods and relaxation of the @xmath0-norm .

Suppose that you have an abstract for a scientific paper: we present a study of the escape time from a metastable state of an overdamped brownian particle , in the presence of colored noise generated by ornstein - uhlenbeck process . we analyze the role of the correlation time on the enhancement of the mean first passage time through a potential barrier and on the behavior of the mean growth rate coefficient as a function of the noise intensity . we observe the noise enhanced stability effect for all the initial unstable states used , and for all values of the correlation time @xmath0 investigated . we can distinguish two dynamical regimes characterized by weak and strong correlated noise respectively , depending on the value of @xmath0 with respect to the relaxation time of the system . . And you have already written the first three sentences of the full article: the problem of the lifetime of a metastable state has been addressed in a variety of areas , including first - order phase transitions , josephson junctions , field theory and chemical kinetics @xcite . recent experimental and theoretical results show that long - live metastable states are observed in different areas of physics @xcite . experimental and theoretical investigations have shown that the average escape time from metastable states in fluctuating potentials presents a nonmonotonic behavior as a function of the noise intensity with the presence of a maximum @xcite .. Please generate the next two sentences of the article

this is the noise enhanced stability ( nes ) phenomenon : the stability of metastable states can be enhanced and the average life time of the metastable state increases nonmonotonically with the noise intensity . this resonance - like behavior contradicts the monotonic behavior of the kramers theory @xcite .

Suppose that you have an abstract for a scientific paper: equilibrium properties of hydrogen - helium mixtures under thermodynamic conditions found in the interior of giant gas planets are studied by means of density functional theory molecular dynamics simulations . special emphasis is placed on the molecular - to - atomic transition in the fluid phase of hydrogen in the presence of helium . helium has a substantial influence on the stability of hydrogen molecules . the molecular bond is strengthened and its length is shortened as a result of the increased localization of the electron charge around the helium atoms , which leads to more stable hydrogen molecules compared to pure hydrogen for the same thermodynamic conditions . the _ ab initio _ treatment of the mixture enables us to investigate the structure of the liquid and to discuss hydrogen - hydrogen , helium - helium , and hydrogen - helium correlations on the basis of pair correlation functions . . And you have already written the first three sentences of the full article: the discovery of the first extrasolar planet in 1995 @xcite marked the beginning of a new era in planetary science , characterized by a rapidly expanding set of known extrasolar planets . more than 200 exoplanets have been discovered so far @xcite . among these , giant gas planets in small orbits are in the majority since the primary tool for detection , radio velocity measurements , is most sensitive to finding heavy planets that rapidly orbit their parent star @xcite . from radius measurements of transient extrasolar planets , it is also known that most of these giant gas planets are like jupiter in consisting primarily of hydrogen and helium . modeling the interior of such planets requires an accurate equation of state for hydrogen - helium mixtures at high pressure and temperature conditions similar to those in planetary interiors @xcite .. Please generate the next two sentences of the article

thus , the characterization of such system by first principle calculations will help us to answer questions concerning the inner structure of planets , their origin and evolution @xcite . in this article , we focus on studying the transition from molecular to atomic hydrogen . in particular , we investigate the effect of different helium concentrations on this transition . in what follows ,

Suppose that you have an abstract for a scientific paper: in this paper , we consider the problem of maximizing an _ unknown _ function @xmath0 over a compact and convex set @xmath1 using as few observations @xmath2 as possible . we observe that the optimization of the function @xmath0 essentially relies on learning the induced bipartite ranking rule of @xmath0 . based on this idea , we relate global optimization to bipartite ranking which allows to address problems with high dimensional input space , as well as cases of functions with weak regularity properties . the paper introduces novel meta - algorithms for global optimization which rely on the choice of any bipartite ranking method . theoretical properties are provided as well as convergence guarantees and equivalences between various optimization methods are obtained as a by - product . eventually , numerical evidence is given to show that the main algorithm of the paper which adapts empirically to the underlying ranking structure essentially outperforms existing state - of - the - art global optimization algorithms in typical benchmarks . global optimization , ranking , statistical analysis , convergence rate bounds . And you have already written the first three sentences of the full article: in many applications such as complex system design or hyperparameter calibration for learning systems , the goal is to optimize some output value of a non - explicit function with as few evaluations as possible . indeed , in such contexts , one has access to the function values only through numerical evaluations by simulation or cross - validation with significant computational cost . moreover , the operational constraints generally impose a sequential exploration of the solution space with small samples .. Please generate the next two sentences of the article

the generic problem of sequentially optimizing the output of an unknown and potentially _ non - convex _ function is often referred to as _ global optimization _ ( @xcite ) , black - box optimization ( @xcite ) or derivative - free optimization ( @xcite ) . there are several algorithms based on various heuristics which have been introduced in order to address complicated optimization problems with limited regularity assumptions , such as genetic algorithms , model - based algorithms , branch - and - bound methods ... see @xcite for a recent overview .

Suppose that you have an abstract for a scientific paper: new high quality keck and eso images of pks 1830211 are presented . applying a powerful new deconvolution algorithm to these optical and infrared data , both images of the flat spectrum core of the radio source have been identified . an extended source is also detected in the optical images , consistent with the expected location of the lensing galaxy . the source counterparts are very red at @xmath0 , suggesting strong galactic absorption with additional absorption by the lensing galaxy at @xmath1 , and consistent with the detection of high redshift molecules in the lens . . And you have already written the first three sentences of the full article: the bright radio source pks 1830211 ( subrahmanyan et al . 1990 ; hereafter s90 , jauncey et al . 1991 ) has attracted much attention as the most detailed example of a lensed radio ring . among the classically - lensed qsos , its short time delay of 44 days ( van ommen et al .. Please generate the next two sentences of the article

1995 ) and clean lens geometry make it a good candidate for measuring h@xmath2 . the lens , a gas rich galaxy at z=0.89 , was discovered in the millimeter via molecular absorption ( wiklind & combes 1996 ) , which is seen towards only one of the two flat spectrum hot spots ( wiklind & combes 1996 , frye et al .

Suppose that you have an abstract for a scientific paper: hubble space telescope observations of black hole x - ray transients are discussed in the context of the disk instability outburst model . we focus on the multiwavelength campaign following gro j1655 - 40 through the summer 1996 outburst . . And you have already written the first three sentences of the full article: as soon as the class was discovered , the obvious similarities between the black hole x - ray transients ( bhxrts ) and their white dwarf analogues , dwarf novae ( dn ) , guided investigations into the mechanisms responsible for the dramatic outbursts exhibited by the former . the outbursts in dn have been successfully explained as the result of temperature - dependent viscosity in the accretion disk : the disk instability model ( dim ) ( cannizzo 1993 ) . the longer recurrence timescales for bhxrts and the shapes and durations of their outburst lightcurves , however , provide a challenge to the dim ( lasota 1996 ) .. Please generate the next two sentences of the article

the dim makes definite quantitative predictions for the temperature distribution , and hence the expected broad band spectrum , throughout the outburst cycle ( _ e.g. _ cannizzo , chen , & livio 1995 ) . accretion disk emission is likely to dominate in the uv , so one of the primary motivations for spectroscopic observations of bhxrts with hst is , therefore , to observe the broad band spectral evolution , and hence address the question of the driving mechanism for the transient outbursts .

Suppose that you have an abstract for a scientific paper: multi - agent systems ( mas ) is able to characterize the behavior of individual agent and the interaction between agents . thus , it motivates us to leverage the distributed constraint optimization problem ( dcop ) , a framework of modeling mas , to solve the user association problem in heterogeneous networks ( hetnets ) . two issues we have to consider when we take dcop into the application of hetnet including : ( i ) how to set up an effective model by dcop taking account of the negtive impact of the increment of users on the modeling process ( ii ) which kind of algorithms is more suitable to balance the time consumption and the quality of soltuion . aiming to overcome these issues , we firstly come up with an ecav-@xmath0 ( each connection as variable ) model in which a parameter @xmath0 with an adequate assignment ( @xmath1 in this paper ) is able to control the scale of the model . after that , a markov chain ( mc ) based algorithm is proposed on the basis of log - sum - exp function . experimental results show that the solution obtained by dcop framework is better than the one obtained by the max - sinr algorithm . comparing with the lagrange dual decomposition based method ( ldd ) , the solution performance has been improved since there is no need to transform original problem into a satisfied one . in addition , it is also apparent that the dcop based method has better robustness than ldd when the number of users increases but the available resource at base stations are limited . . And you have already written the first three sentences of the full article: of agent and the cooperation between agents in multi - agent system ( mas ) , a framework , named distributed constraint optimization problem ( dcop ) in terms of constraints that are known and enforced by distinct agents comes into being with it . in last decade , the research effort of dcop has been dedicated on the following three directions : 1 ) the development of dcop algorithms which are able to better balance the computational complexity and the accuracy of solution , such as large neighborhood search method @xcite ; markov chain monte carlo sampling method @xcite @xcite and distributed junction tree based method @xcite 2 ) the extension of classical dcop model in order to make it more flexible and effective for practical application , such as expected regret dcop model @xcite , multi - variable agent decomposition model @xcite and dynamic dcop model @xcite 3 ) the application of dcop in modeling environmental systems , such as sensor networks @xcite , disaster evacuation @xcite , traffic control @xcite and resource allocation @xcite . in this paper , we take more attention to the application of dcop .. Please generate the next two sentences of the article

more precisely , we leverage dcop to solve user association problem in the downlink of multi - tier heterogeneous networks with the aim to assign mobile users to different base stations in different tiers while satisfying the qos constraint on the rate required by each user . is generally regarded as a resource allocation problem @xcite in which the resource is defined by the resource blocks ( rbs ) . in this case , the more rbs allocated to a user , the larger rate achieved by the user .

Suppose that you have an abstract for a scientific paper: we provide a squeeze - like transformation that allows one to remove a position dependent mass from the hamiltonian . methods to solve the schrdinger equation may then be applied to find the respective eigenvalues and eigenfunctions . as an example , we consider a position - dependent - mass that leads to the integrable morse potential and therefore to well - known solutions . . And you have already written the first three sentences of the full article: considerable interest has been recently devoted in finding exact solutions to schrdinger equations involving known potentials when the mass is position - dependent ( pdm ) . among them , one may mention the morse and coulomb potentials @xcite . moreover , it has been recently shown @xcite that to lowest order of perturbation theory , there exists a whole class of hermitian position - dependent - mass hamiltonians that are associated with pseudo - hermitian hamiltonians .. Please generate the next two sentences of the article

a great deal of interest has been paid to the interplay between these pseudo - hermitian pt - symmetric hamiltonians and their equivalent hermitian representations @xcite . in particular , mostafazadeh @xcite has considered the transition to the classical limit by showing that the relevant classical hamiltonian for the pt - symmetric cubic anharmonic oscillator plus a harmonic term , produces a behavior similar to a point particle with position - dependent - mass interacting with a quartic harmonic oscillator . indeed , many physical settings exist in which the effective mass can in principle depend on position . for example , wang et al .

Suppose that you have an abstract for a scientific paper: we explored a method to reconstruct the distribution function of the galactic thick disc within the action space where nearby thick - disc stars are distributed . by applying this method to 127 chemically - selected thick - disc stars in the solar neighbourhood , we found that the vertical velocity dispersion that corresponds to the reconstructed distribution function declines approximately as @xmath0 at @xmath1 , with @xmath2 kpc . also , we found that the vertical velocity dispersion @xmath3 of our local thick - disc stars shows only weak dependency on radial and azimuthal velocities @xmath4 . we discuss possible implications of these results on the global structure of the milky way thick disc . [ firstpage ] galaxy : disc galaxy : evolution galaxy : formation galaxy : kinematics and dynamics galaxy : structure solar neighbourhood . And you have already written the first three sentences of the full article: historically , the thick disc of the milky way was first identified through star counts toward the galactic poles as a vertically extended disc component with scale height @xmath5 1 kpc @xcite , in addition to the thin disc with scale height @xmath6 that dominates the disc stars in the immediate solar neighbourhood . therefore , at the outset , the tentative definition of the thick - disc stars was those disc stars with large vertical orbital excursions and large vertical velocities . later , spectroscopic studies ( e.g. , @xcite ) on kinematically - selected disc stars suggested that stars with large vertical motions ( which are likely to belong to the thick disc ) tend to show lower [ fe / h ] and higher [ @xmath7/fe ] than those with small vertical motions ( thin - disc stars ) .. Please generate the next two sentences of the article

these chemical properties suggest that the thick - disc stars are older than thin - disc stars ( lower [ fe / h ] ) and that the star formation timescale of the thick disc was shorter than that of the thin disc ( higher [ @xmath7/fe ] ) . recently , klaus fuhrmann @xcite investigated a kinematically - unbiased volume - complete sample of solar - type disc and halo stars located within 25 pc of the sun .

Suppose that you have an abstract for a scientific paper: the muon charge ratio of ultrahigh energy cosmic rays may provide information to detect the composition of the primary cosmic rays . we propose to extract the charge information of high energy muons in very inclined extensive air showers by analyzing their relative lateral positions in the shower transverse plane . the most high energy particles can be observed by human being are from cosmic rays . the study of them belongs to frontiers of human knowledge in combination of cosmology , astrophysics , and particle physics , and can provide better understanding of the universe from most small to most big , i.e. , connecting quarks to the cosmos . the universe is not empty , but full of background relic particles from the big bang . it has long been anticipated that the highest energy cosmic rays would be protons from outside the galaxy , and there is an upper limit of the highest energy in the observed proton spectrum , commonly referred to as the gzk cutoff @xcite , as the protons traveling from intergalactic distances should experience energy losses owing to pion productions by the photons in the cosmic background radiation . although there have been attentions for the cosmic ray events above the gzk cutoff , it is natural to expect that these ultrahigh energy cosmic rays come from sources within the gzk zone @xcite , i.e. , not far from us in more than tens of mpc . recently there are also reports on the observation of the gzk cut - off by new experiments @xcite . however , questions about the composition of such ultrahigh energy cosmic ray particles , e.g. , whether they are protons , neutrons , or anti - nucleons @xcite , are still open to investigations . muons in the air showers are mainly from decays of pions and kaons produced in the interactions of the primary cosmic rays with the atmosphere . the very high energy secondary pion and kaon cosmic rays can be considered as from the current fragmentation of partons in deep inelastic scattering of the primary cosmic rays with the.... And you have already written the first three sentences of the full article: i am very grateful to pauchy hwang and the organizers for their invitation and warm hospitality . i also thank pauchy hwang and bingkan xue for the collaborated results in this talk . this work is partially supported by national natural science foundation of china ( nos . 10721063 , 10575003 , 10528510 ) , by the key grant project of chinese ministry of education ( no .. Please generate the next two sentences of the article

305001 ) , and by the research fund for the doctoral program of higher education ( china ) . j. r. horandel , j. phys .

Suppose that you have an abstract for a scientific paper: sma observations of the massive star - forming region iras18089 - 1732 in the 1 mm and 850@xmath0 m band reveal outflow and disk signatures in different molecular lines . the sio(54 ) data show a collimated outflow in the northern direction . in contrast , the hcooch@xmath1(2019 ) line , which traces high - density gas , is confined to the very center of the region and shows a velocity gradient across the core . the hcooch@xmath1 velocity gradient is not exactly perpendicular to the outflow axis but between an assumed disk plane and the outflow axis . we interpret these hcooch@xmath1 features as originating from a rotating disk that is influenced by the outflow and infall . based on the ( sub-)mm continuum emission , the mass of the central core is estimated to be around 38m@xmath2 . the dynamical mass derived from the hcooch@xmath1 data is 22m@xmath2 , of about the same order as the core mass . thus , the mass of the protostar / disk / envelope system is dominated by its disk and envelope . the two frequency continuum data of the core indicate a low dust opacity index @xmath3 in the outer part , decreasing to @xmath4 on shorter spatial scales . . And you have already written the first three sentences of the full article: unambiguous proof for disks in massive star formation is still missing . millimeter continuum observations suggest flattened structures without providing velocity information ( e.g. , @xcite ) , and molecular line studies suggest rotational motions but are often confused outflows and ambient gas ( e.g. , @xcite and beuther et al . , this volume ) .. Please generate the next two sentences of the article

maser studies show disk signatures in some cases but are mostly not unambiguous as well ( e.g. , @xcite ) . the best evidence yet for genuine disk emission comes from ch@xmath1cn observations in iras20126 + 4104 @xcite . in this case

Suppose that you have an abstract for a scientific paper: the finite type invariant concept for knots was introduced in the 90 s in order to classify knot invariants , with the work of vassiliev , goussarov and bar - natan , shortly after the birth of numerous quantum knot invariants . this very useful concept was extended to @xmath0manifold invariants by ohtsuki . these introductory lectures show how to define finite type invariants of links and @xmath0-manifolds by counting graph configurations in @xmath0-manifolds , following ideas of witten and kontsevich . the linking number is the simplest finite type invariant for @xmath1component links . it is defined in many equivalent ways in the first section . as an important example , we present it as the algebraic intersection of a torus and a @xmath2-chain called a _ propagator _ in a configuration space . in the second section , we introduce the simplest finite type @xmath0manifold invariant , which is the casson invariant ( or the @xmath3invariant ) of integer homology @xmath0spheres . it is defined as the algebraic intersection of three propagators in the same two - point configuration space . in the third section , we explain the general notion of finite type invariants and introduce relevant spaces of feynman jacobi diagrams . in sections 4 and 5 , we sketch an original construction based on configuration space integrals of universal finite type invariants for links in rational homology @xmath0spheres and we state open problems . our construction generalizes the known constructions for links in @xmath4 and for rational homology @xmath0spheres , and it makes them more flexible . in section 6 , we present the needed properties of parallelizations of @xmath0manifolds and associated pontrjagin classes , in details . * keywords : * knots , @xmath0-manifolds , finite type invariants , homology @xmath0spheres , linking number , theta invariant , casson - walker invariant , feynman jacobi diagrams , perturbative expansion of chern - simons theory , configuration space integrals ,.... And you have already written the first three sentences of the full article: these notes contain some details about talks that were presented in the international conference `` quantum topology '' organized by laboratory of quantum topology of chelyabinsk state university in july 2014 . they are based on the notes of five lectures presented in the icpam - ictp research school of mekns in may 2012 . i thank the organizers of these two great events .. Please generate the next two sentences of the article

i also thank catherine gille and kvin corbineau for useful comments on these notes . these notes have been written in an introductory way , in order to be understandable by graduate students .

Suppose that you have an abstract for a scientific paper: among its great findings , the iras mission showed the existence of an unidentified mid - ir feature around 21 @xmath0 m . since its discovery , this feature has been detected in all c - rich proto - pne of intermediate spectral type ( a g ) and - weakly - in a few pne and agb stars , but the nature of its carriers remains unknown . in this paper , we show the detection of this feature in the spectra of three new stars transiting from the agb to the pn stage obtained with the spitzer space telescope . following a recent suggestion , we try to model the seds of our targets with amorphous carbon and feo , which might be responsible for the unidentified feature . the fit thus obtained is not completely satisfactory , since the shape of the feature is not well matched . in the attempt to relate the unidentified feature to other dust features , we retrieved mid - ir spectra of all the 21-@xmath0 m sources currently known from iso and spitzer on - line archives and noticed a correlation between the flux emitted in the 21-@xmath0 m feature and that emitted at 7 and 11 @xmath0 m ( pah bands and hac broad emission ) . such a correlation may point to a common nature of the carriers . . And you have already written the first three sentences of the full article: one of the major results of the _ infrared astronomical satellite _ ( iras ) mission came from its low resolution spectrometer ( lrs ) with the detection of a new broad feature around 21 @xmath0 m @xcite in the spectra of stars that have gone through the asymptotic giant branch ( agb ) phase . the existence of this feature was not recognized at once , because it is weak in the first object in which it was observed , iras 22272 + 5435 , which was listed in the lrs atlas as having a low - temperature continuum and silicate absorption @xcite . in the first paper about this feature , four sources are listed ( namely iras 07134 + 1005 , 23304 + 6147 , 22272 + 5435 , and 04296 + 3429 ) ; subsequent ground - based ( united kingdom infrared telescope ) , airborne ( kuiper airborne observatory ) , and space - based ( infrared space observatory ) observations confirmed those detections and also added new members to the group of 21-@xmath0 m emitters .. Please generate the next two sentences of the article

observations with the _ infrared space observatory _ ( iso ) led to conclude that the feature actually peaks around 20.1 @xmath0 m @xcite , although it is still today commonly referred to as the 21 @xmath0 m feature . the feature has been detected almost exclusively in c - rich proto - planetary nebulae ( ppne ) , intermediate - mass stars ( 18 m@xmath1 ) transiting from the agb to the planetary nebula ( pn ) stage . during the agb phase ,

Suppose that you have an abstract for a scientific paper: the thermodynamic properties of the _ quark gluon plasma _ ( @xmath0 ) as well as its phase diagram are calculated as a function of baryon density ( chemical potential ) and temperature . the @xmath0 is assumed to be composed of the light quarks only , i.e. the up and the down quarks , which interact weakly and the gluons which are treated as they are free . the interaction between quarks is considered in the framework of the _ one gluon exchange _ model which is obtained from the fermi liquid picture . the bag model is used , with fixed bag pressure ( @xmath1 ) for the _ nonperturbative _ part and the _ quantum chromodynamics _ ( @xmath2 ) coupling is assumed to be constant i.e. no dependence on the temperature or the baryon density . the effect of weakly interacting quarks on the @xmath0 phase diagram are shown and discussed . it is demonstrated that the _ one gluon exchange _ interaction for the massless quarks has considerable effect on the @xmath0 phase diagram and it causes the system to reach to the confined phase at the smaller baryon densities and temperatures . the pressure of excluded volume hadron gas model is also used to find the transition phase - diagram . our results depend on the values of bag pressure and the @xmath2 coupling constant which the latter does not have a dramatic effect on our calculations . finally , we compare our results with the thermodynamic properties of strange quark matter and the lattice @xmath2 prediction for the @xmath0 transition critical temperature . . And you have already written the first three sentences of the full article: the _ quark gluon plasma _ ( @xmath0 ) usually is defined as the phase of _ quantum chromodynamics _ ( @xmath2 ) in which the quarks and gluons degrees of freedom , that is normally confined within the hadrons , are mostly liberated . the possible phases of the @xmath2 and the precise locations of critical boundaries or points are currently being actively studied .. Please generate the next two sentences of the article

in fact , revealing the @xmath2 phase transition structure is one of the central aims of the ongoing and the future theoretical and the experimental research in the field of the hot and/or the dense @xmath2 @xcite . it is about thirty years since the study of the hot and the dense nuclear matter in the form of the @xmath0 has been started .

Suppose that you have an abstract for a scientific paper: the position and momentum space information entropies of the electron distributions of atomic clusters are calculated using a woods saxon single particle potential . the same entropies are also calculated for nuclear distributions according to the skyrme parametrization of the nuclear mean field . it turns out that a similar functional form @xmath0 for the entropy as function of the number of particles @xmath1 holds approximately for atoms , nuclei and atomic clusters . it is conjectured that this is a universal property of a many - fermion system in a mean field . it is also seen that there is an analogy of our expression for @xmath2 to boltzmann s thermodynamic entropy @xmath3 . pacs : 89.70.+c ; 36.40.+d ; 31.10.+z ; 21.60.-n information theoretical methods have played in recent years an important role in the study of quantum mechanical systems @xcite in two cases : first in the clarification of fundamental concepts of quantum mechanics and second in the synthesis of probability densities in position and momentum spaces . in the first case an important step was the discovery of an entropic uncertainty relation ( eur ) by bialynicki birula and mycielski @xcite which for a three dimensional system has the form : @xmath4 ( see also ref . @xcite for the one dimensional case ) . in ( [ ( 1 ) ] ) @xmath5 is the shannon information entropy in position space : @xmath6 @xmath7 is the corresponding entropy in momentum - space : @xmath8 and @xmath9 , @xmath10 are the position and momentum space density distributions respectively , which are normalized to one . however , for a normalization to the number of particles @xmath1 , the following eur holds @xcite : @xmath11 inequality ( 1 ) , for the information entropy sum in conjugate spaces , is a joint measure of uncertainty of a quantum mechanical distribution , since a highly localized @xmath9 is associated with a diffuse @xmath10 , leading to low @xmath5 and high @xmath7 and vice versa . expression ( [ ( 1 ) ] ) is an.... And you have already written the first three sentences of the full article: the authors would like to thank professor m.e . grypeos for an informative discussion in atomic clusters 99 i. bialynicki - birula and j. mycielski , commun . meth . phys . * 44 * 129 ( 1975 ) s. r. gadre , phys . rev .. Please generate the next two sentences of the article

a * 30 * 620 ( 1984 ) s. r. gadre , s. b. sears , s. j. chacravorty and r. d. bendale , phys . a bf 32 2602 ( 1985 ) s. r. gadre and r. d. bendale , phys .

Suppose that you have an abstract for a scientific paper: we present ac susceptibility measurements with the frequency spanning three orders of magnitude on single grain , icosahedral r - mg - zn ( r = rare earth ) quasicrystals . the freezing temperature in gd - based , heisenberg spin glasses in this family increases by @xmath0 with a frequency increase from 10 hz to 10 khz , whereas the freezing temperature in the non - heisenberg members of the family is significantly more responsive to the frequency change ( by 16 - 22 % ) , suggesting that an additional magnetic anisotropy distribution in the non - heisenberg spin glasses causes changes in the low frequency magnetic dynamics . spin glass ; quasicrystals ; freezing temperature ; frequency dependence . And you have already written the first three sentences of the full article: magnetic moment bearing , rare earth containing , quasicrystals , being an example of well ordered solids with sharp diffraction peaks but with conventional requirement of translational symmetry lifted , present a rare example of an `` ideal '' spin glass , in which the spin glass state probably arises from the multiplicity of the r - r distances in the quasicrystalline lattice , @xcite as opposed to a substitutional disorder in crystalline metallic spin glasses . @xcite successful growth of large , single grain , r@xmath1mg@xmath2zn@xmath3 ( r = rare earth ) icosahedral quasicrystals @xcite allowed for detailed studies of the physical properties of the spin glass state in these materials , leading , in particular , to a clear delineation of the experimental differences between heisenberg and non - heisenberg spin glasses . @xcite it was shown that the freezing temperature , @xmath4 , is lower for the gd - based , heisenberg spin glasses , than for r = tb - er , non heisenberg spin glasses for the samples with the same values of the de gennes factor [ @xmath5 , or the weiss temperature . as a consequence , for e.g. ( tb@xmath6gd@xmath7)@xmath1mg@xmath2zn@xmath3 and ( dy@xmath6gd@xmath7)@xmath1mg@xmath2zn@xmath3 pseudo - ternary solid solution. Please generate the next two sentences of the article

the maximum in @xmath4 was observed for @xmath8 when a crossover from from heisenberg to non - heisenberg behavior occurs . @xcite based on the large data sets in refs .

Suppose that you have an abstract for a scientific paper: the gari - krmpelmann ( gk ) models of nucleon electromagnetic form factors , in which the @xmath0 , @xmath1 , and @xmath2 vector meson pole contributions evolve at high momentum transfer to conform to the predictions of perturbative qcd ( pqcd ) , was recently extended to include the width of the @xmath0 meson by substituting the result of dispersion relations for the pole and the addition of the @xmath3 ( 1450 ) isovector vector meson pole . this extended model was shown to produce a good overall fit to all the available nucleon electromagnetic form factor ( emff ) data . since then new polarization data shows that the electric to magnetic ratios @xmath4 and @xmath5 obtained are not consistent with the older @xmath6 and @xmath7 data in their range of momentum transfer . the model is further extended to include the @xmath8 ( 1419 ) isoscalar vector meson pole . it is found that while this gkex can not simultaneously fit the new @xmath4 and the old @xmath7 data , it can fit the new @xmath4 and @xmath5 well simultaneously . an excellent fit to all the remaining data is obtained when the inconsistent @xmath6 and @xmath7 is omitted . the model predictions are extended beyond the data , if needed , to momentum transfer squared , @xmath9 , of 8 gev@xmath10 . . And you have already written the first three sentences of the full article: a variety of related models of the nucleon emff @xcite were fitted to the complete set of data available before september 2001 . one group of models included variants of the basic gk model of @xmath0 , @xmath1 , and @xmath2 vector meson pole terms with hadronic form factors and a term with pqcd behavior which dominates at high @xmath9 @xcite . four varieties of hadronic form factor parameterization ( of which two are used in @xcite ) were compared .. Please generate the next two sentences of the article

in addition to the gk type models we considered a group of models ( generically designated dr - gk ) that use the analytic approximation of @xcite to the dispersion integral approximation for the @xmath0 meson contribution ( similar to that of @xcite ) , modified by the four hadronic form factor choices used with the gk model , and the addition of the well established @xmath3 ( 1450 ) pole . every model had an electric and a magnetic coupling parameter for each of the three pole terms , four cut - off " masses for the hadronic form - factors and the qcd scale mass scale , @xmath11 for the logarithmic momentum transfer behavior in pqcd . in addition the effect of a normalization parameter was sometimes considered for the dispersion relation behavior of the @xmath0 meson in the dr - gk models . when the set of parameters in each of the eight models was fitted to the full set of data available before publication , for @xmath6 , @xmath12 , @xmath7 , @xmath13 and the lower @xmath9 values of @xmath14 , three gk and all four dr - gk models attained reasonable @xmath15 ( when the inconsistency of some low @xmath9 @xmath7 and @xmath13 data was taken into account ) , but the extended dr - gk models had significantly lower @xmath15 .

Suppose that you have an abstract for a scientific paper: a higher dimensional frame formalism is developed in order to study implications of the bianchi identities for the weyl tensor in vacuum spacetimes of the algebraic types iii and n in arbitrary dimension @xmath0 . it follows that the principal null congruence is geodesic and expands isotropically in two dimensions and does not expand in @xmath1 spacelike dimensions or does not expand at all . it is shown that the existence of such principal geodesic null congruence in vacuum ( together with an additional condition on twist ) implies an algebraically special spacetime . we also use the myers - perry metric as an explicit example of a vacuum type d spacetime to show that principal geodesic null congruences in vacuum type d spacetimes do not share this property . . And you have already written the first three sentences of the full article: for dimensions @xmath2 the weyl tensor vanishes identically and for @xmath3 it has very special properties . it is of interest to determine which of the properties of four - dimensional ( 4d ) spacetimes can be straightforwardly generalized to higher dimensions and which need to be modified or do not hold at all . recently a classification of algebraic tensor types in lorentzian manifolds of arbitrary dimension was developed @xcite .. Please generate the next two sentences of the article

for the weyl tensor in 4d this classification reproduces the petrov classification and for the ricci tensor in 4d the segre classification . in 4d it follows from the bianchi identities . in the first case

Suppose that you have an abstract for a scientific paper: some issues of inverting asteroseismic frequency data are discussed , including the use of model calibration and linearized inversion . an illustrative inversion of artificial data for solar - type stars , using least - squares fitting of a small set of basis functions , is presented . a few details of kernel construction are also given . . And you have already written the first three sentences of the full article: the accumulated experience in helioseismology of inverting mode frequency data provides a good starting point for asteroseismic inversion . in some rather superficial ways the circumstances of the two may seem very different : helioseismologists can use many more mode frequencies than will ever be possible for a more distant star , so that the resolution that can be achieved in helioseismic inversion is beyond the grasp of asteroseismology ( an exception may be situations such as where modes are trapped in a narrow range of depth within the star ) . another difference is that global parameters of the sun such as its mass , radius and age are much better known than they are for other stars ; hence the structure of the sun is constrained _ a priori _ much more accurately than it is for a distant star , even if the input physics had been known precisely , which of course is not the case for the sun or for other stars . in more fundamental ways , though , helioseismic and asteroseismic inversion are much more similar than they are different .. Please generate the next two sentences of the article

helioseismology has not always been blessed with such a wealth of data , and helioseismologists in the early days of their subject learned the value of model calibration and asymptotic description ( in particular of low - degree modes ) for making inferences about the sun . they also learned some of the dangers and limitations of drawing inferences from real data .

Suppose that you have an abstract for a scientific paper: we identified a new class of mid - latitude medium - scale traveling ionospheric disturbances ( ms tids ) , viz . traveling wave packets ( twps ) of total electron content ( tec ) disturbances . for the first time , the morphology of twps is presented for 105 days from the time interval 1998 - 2001 with a different level of geomagnetic activity , with the number of stations of the global gps network ranging from 10 to 300 . the radio paths used in the analysis total about 700000 . these data were obtained using the globdet technology for global detection and monitoring of ionospheric disturbances of natural and technogenic origin from measurements of tec variations acquired by a global network of receivers of the navigation gps system . the globdet technology was developed at the istp sb ras . using the technique of gps interferometry of tids we carried out a detailed analysis of the spatial - temporal properties of twps by considering an example of the most conspicuous manifestation of twps on october 18 , 2001 over california , usa . it was found that twps are observed no more than in 0.1 - 0.4% of all radio paths , most commonly during the daytime in winter and autumn at low geomagnetic activity . twps in the time range represent quasi - periodic oscillations of tec of a length on the order of 1 hour with the oscillation period in the range 10 - 20 min and the amplitude exceeding the amplitude of `` background '' tec fluctuations by one order of magnitude , as a minimum . the radius of spatial correlation of twps does not exceed 500600 km ( 35 wavelengths ) . the velocity and direction of twps correspond to those of mid - latitude medium - scale traveling ionospheric disturbances ( ms tids ) obtained previously from analyzing the phase characteristics of hf radio signals as well as signals from geostationary satellites and discrete cosmic radio sources . . And you have already written the first three sentences of the full article: the unremitting interest in investigations of atmospheric acoustic - gravity waves ( agw ) over more than four decades dating back to hines pioneering work ( hines , 1960 , 1967 ) is dictated by the important role played by these waves in the dynamics of the earth s atmosphere . these research efforts have been addressed in a large number of publications , including a series of through reviews ( hocke and schlegel , 1996 ; oliver et al . , 1997 ) . agw typically show up in the ionosphere in the form of traveling ionospheric disturbances ( tids ) and are detected by various radio techniques .. Please generate the next two sentences of the article

tids are classified as large- and medium - scale disturbances differing by their horizontal phase velocity which is larger ( in the large - scale case ) or smaller ( for the medium scale ) velocity of sound in the lower thermosphere ( on the order of 300 m / s ) , with periods within 0.53.0 h and 1040 min , respectively . medium - scale tids ( ms tids ) are observed predominantly during the daytime hours and are associated with agw which are generated in the lower atmosphere .

Suppose that you have an abstract for a scientific paper: merging neutron star binaries are prime candidate sources for heavy @xmath0-process nucleosynthesis . the amount of heavy @xmath0-process material is consistent with the mass ejection and rates of mergers , and abundances of relic radioactive materials suggest that heavy @xmath0-process material is produced in rare events . observations of possible macronovae provide further support for this model . still , some concerns remain . one is the observation of heavy @xmath0-process elements in ultra faint dwarf ( ufd ) galaxies . the escape velocities from ufds are so small that the natal kicks , taking place at neutron stars birth , might eject such binaries from ufds . furthermore the old stellar populations of ufds requires that @xmath0-process nucleosynthesis must have taken place very early on , while it may take several gyr for compact binaries to merge . this last problem arises also within the milky way where heavy @xmath0-process materials has been observed in some low metallicity stars . we show here that @xmath1 of neutron star binaries form with a sufficiently small proper motion to remain bound even in a ufd . furthermore , approximately @xmath2 of dnss with an initial separation of @xmath3 cm merge within 300myrs and @xmath4 merge in less than 100myrs . this population of rapid mergers " explains the appearance of heavy @xmath0-process material in both ufds and in the early milky way . . And you have already written the first three sentences of the full article: merging double neutron stars ( dnss ) that eject highly neutron rich material are prime candidates for the production sites of heavy @xmath0(apid)-process elements @xcite . the overall amount of heavy @xmath0-process material in the milky way is consistent with the expectations of mass ejection in numerical merger simulations ( e.g. * ? ? ? * ; * ? ? ?. Please generate the next two sentences of the article

* ) with their expected rates as estimated from galactic dnss ( see e.g. * ? ? ? * ) or from the rate @xcite of short gamma - ray bursts ( sgrbs ) .

Suppose that you have an abstract for a scientific paper: in this paper we use floer homology to prove existence of solutions of a generalized abelian higgs equation introduced by schroers . . And you have already written the first three sentences of the full article: a floer homology is the morse homology of an action functional @xmath0 defined on the infinite dimensional space @xmath1 of smooth maps from a manifold @xmath2 to a target manifold @xmath3 . the floer chain complex is generated by critical points of @xmath0 which are smooth maps from @xmath2 to @xmath3 solving a pde ( respectively an ode if @xmath2 is 1-dimensional ) . the floer boundary operator is defined by counting gradient flow lines of @xmath0 .. Please generate the next two sentences of the article

these are smooth maps from @xmath4 to @xmath3 again solving a pde . in the special case where @xmath5 is the circle and @xmath0 is the classical hamiltonian action functional the critical points of @xmath0 are the periodic orbits of the hamiltonian system . this was used by floer in his proof of the arnold conjecture @xcite .

Suppose that you have an abstract for a scientific paper: recently , clustering of inertial particles in turbulence has been thoroughly analyzed for statistically homogeneous isotropic flows . phenomenologically , spatial homogeneity of particles configurations is broken by the advection of a range of eddies determined by the stokes relaxation time of the particles which results in a multi - scale distribution of local concentrations and voids . much less is known concerning anisotropic flows . here , by addressing direct numerical simulations ( dns ) of a statistically steady particle - laden homogeneous shear flow , we provide evidence that the mean shear preferentially orients particle patterns . by imprinting anisotropy on large scales velocity fluctuations , the shear indirectly affects the geometry of the clusters . quantitative evaluation is provided by a purposely designed tool , the angular distribution function of particle pairs ( adf ) , which allows to address the anisotropy content of particles aggregates on a scale by scale basis . the data provide evidence that , depending on the stokes relaxation time of the particles , anisotropic clustering may occur even in the range of scales where the carrier phase velocity field is already recovering isotropy . the strength of the singularity in the anisotropic component of the adf quantifies the level of fine scale anisotropy , which may even reach values of more than @xmath0 direction - dependent variation in the probability to find two close - by particles at viscous scale separation . . And you have already written the first three sentences of the full article: transport of inertial particles is involved in several fields of science , e.g. droplets growth in clouds , @xcite , planetary formations , @xcite , or plankton accumulation in the ocean , @xcite . as far as technological applications are concerned , inertial particle dynamics is crucial for solid or liquid fuelled rockets , injection systems of internal combustion engines or for sediments accumulation in pipelines , e.g. @xcite . inertial particles differ from perfectly lagrangian tracers due to inertia which prevents them from following the flow trajectories . the main effect consists of `` preferential accumulation '' , see for instance @xcite . in homogeneous isotropic conditions it amounts to the small - scale clustering discussed in a number of recent papers , @xcite. Please generate the next two sentences of the article

. in presence of inhomogeneity new features emerge leading to the so - called turbophoresis as a preferential accumulation near the boundary in wall turbulence @xcite . under appropriate conditions , particles may achieve extremely large concentrations at the wall with a substantial reduction of mobility .

Suppose that you have an abstract for a scientific paper: we consider a stochastic version of the wilson - cowan model which accommodates for discrete populations of excitatory and inhibitory neurons . the model assumes a finite carrying capacity with the two populations being constant in size . the master equation that governs the dynamics of the stochastic model is analyzed by an expansion in powers of the inverse population size , yielding a coupled pair of non - linear langevin equations with multiplicative noise . gillespie simulations show the validity of the obtained approximation , for the parameter region where the system exhibits dynamical bistability . we report analytical progress by silencing the retroaction of the activators on the inhibitors , while still assigning the parameters so to fall in the region of deterministic bistability for the excitatory species . the proposed approach forms the basis of a perturbative generalization which applies to the case where a modest degree of coupling is restored . . And you have already written the first three sentences of the full article: neural models aim at elucidating the grounding architecture that regulates information processing in biological nervous systems @xcite . the level of abstraction that is accommodated for in the chosen mathematical scheme reflects the specific topic under investigations . detailed single neurons models can be devised , which account for the sharp changes in the action potential .. Please generate the next two sentences of the article

the number of neurons in the human cortex is extraordinarily large and for many practical aspects a bottom - up approach that moves from a detailed representation of each individual unit is virtually impracticable . the physiology of neurons is also quite intricate .

Suppose that you have an abstract for a scientific paper: within the scope of bianchi type-@xmath0 spacetime we study the role of spinor field on the evolution of the universe . it is found that the presence of nontrivial non - diagonal components of energy - momentum tensor of the spinor field plays vital role on the evolution of the universe . as a result of their mutual influence there occur two different scenarios . in one case the invariants constructed from the bilinear forms of the spinor field become trivial , thus giving rise to a massless and linear spinor field lagrangian . according to the second scenario massive and nonlinear terms do not vanish and depending on the sign of coupling constants we have either an expanding mode of expansion or the one that after obtaining some maximum value contracts and ends in big crunch generating spacetime singularity . this result shows that the spinor field is highly sensitive to the gravitational one . -24pt . And you have already written the first three sentences of the full article: thanks to its flexibility to simulate the different characteristics of matter from perfect fluid to dark energy and its ability to describe the different stages of the evolution of the universe , spinor field has become quite popular among the cosmologists @xcite . but some recent study @xcite suggests that flexible though it is , the existence of non - diagonal components of the energy - momentum tensor of the spinor field imposes very severe restrictions on the geometry of the universe as well as on the spinor field , thus justifying our previous claim that spinor field is very sensitive to the gravitational one @xcite . in some recent papers @xcite within the scope of bianchi type - i cosmological model the role of spinor field in the evolution of the universe has been studied .. Please generate the next two sentences of the article

it is found that due to the spinor affine connections the energy momentum tensor of the spinor field becomes non - diagonal , whereas the einstein tensor is diagonal . this non - triviality of non - diagonal components of the energy - momentum tensor imposes some severe restrictions either on the spinor field or on the metric functions or on both of them . in case

Suppose that you have an abstract for a scientific paper: we present evidence for the existence of a light scalar particle that most probably couples exclusively to gluons and quarks . theoretical and phenomenological arguments are presented to support the existence of a light scalar boson for confinement and quark - pair creation . previously observed interference effects allow to set a narrow window for the scalar s mass and also for its flavor - mass - dependent coupling to quarks . here , in order to find a direct signal indicating its production , we study published babar data on leptonic bottomonium decays , viz.the reactions @xmath0 @xmath1 @xmath2 @xmath1 @xmath3 ( and @xmath4 ) . we observe a clear excess signal in the invariant - mass projections of @xmath0 and @xmath5 , which may be due to the emission of a so far unobserved scalar particle with a mass of about 38 mev . in the process of our analysis , we also find an indication of the existence of a @xmath6 hybrid state at about 10.061 gev . further signals could be interpreted as replicas with masses two and three times as large as the lightest scalar particle . . And you have already written the first three sentences of the full article: in ref . @xcite an @xmath7 conformally symmetric model was proposed for strong interactions at low energies , based on the observation , published in 1919 by h. weyl in ref . @xcite , that the dynamical equations of gauge theories retain their flat - space - time form when subject to a conformally - flat metrical field , instead of the usual minkowski background . confinement of quarks and gluons is then described through the introduction of two scalar fields which spontaneously break the @xmath7 symmetry down to @xmath8 and @xmath9 symmetry , respectively . moreover ,. Please generate the next two sentences of the article

a symmetric second - order tensor field is defined that serves as the metric for flat space - time , coupling to electromagnetism . quarks and gluons , which to lowest order do not couple to this tensor field , are confined to an anti - de - sitter ( ads ) universe @xcite , having a finite radius in the flat space - time .

Suppose that you have an abstract for a scientific paper: we study the corrections of first order electromagnetic excitation due to higher order electromagnetic interactions . an effective operator is introduced which takes these effects into account in the sudden approximation . evaluating the matrix - elements of this operator between the relevant states corrections to the first order result are obtained in a simple way . as an example we discuss the excitation of the first excited state in @xmath0be . it tends to improve the agreement between experiment and theory . 425.70 in 0.80 in 0.20 in electromagnetic excitation in the energy domain of several tens of mev / u up to relativistic energies is a growing field of study . the cross - section can become large and irreducible nuclear effects can be kept under control . with increasing beam energy the equivalent photon spectrum becomes harder , and also particle - unstable states can be reached . the coulomb dissociation @xmath0li @xmath1 @xmath2li + 2n and @xmath3o @xmath1 @xmath4n + p , which is also astrophysically relevant , are examples @xcite . recently , bound states were also excited and their ( doppler shifted ) de - excitation @xmath5-rays were measured . a large deformation of the neutron - rich nucleus @xmath6 mg was recently deduced from a measurement of the @xmath7 885 kev transition to the ground state after medium energy electromagnetic excitation @xcite . the 320 kev @xmath8 @xmath5-transition in @xmath0be was recently observed . the measured cross - section for the @xmath0be ( @xmath9 ) coulomb excitation was found to be noticeably less than expected from the known lifetime and @xmath10 order pure coulomb excitation @xcite . apart from possible nuclear and coulomb - nuclear interference effects , a possible reason for this discrepancy is the influence of higher order electromagnetic interaction . it is the purpose of this letter to describe a framework suitable for fast projectiles . e.g. the rather loosely bound @xmath0be in its @xmath10 excited @xmath11 state.... And you have already written the first three sentences of the full article: * figure 1 : * reduction factor @xmath54 for the excitation probability as a function of the characteristic parameter @xmath26 defined in eq . [ zdef ] for the two model wave functions ( i : , ii : - - - ) . + * figure 2 : * reduction @xmath102 of the total cross section for the excitation of the @xmath11 first excited state from the @xmath103 ground state of @xmath0be as a function of the projectile velocity @xmath17 for the two model wave functions ( i : , ii : - - - ) .. Please generate the next two sentences of the article

Suppose that you have an abstract for a scientific paper: standard quantum state reconstruction techniques indicate that a detection efficiency of @xmath0 is an absolute threshold below which quantum interferences can not be measured . however , alternative statistical techniques suggest that this threshold can be overcome at the price of increasing the statistics used for the reconstruction . in the following we present numerical experiments proving that quantum interferences can be measured even with a detection efficiency smaller than @xmath0 . at the same time we provide a guideline for handling the tomographic reconstruction of quantum states based on homodyne data collected by low efficiency detectors . . And you have already written the first three sentences of the full article: homodyne detection is an experimental method that is used to reconstruct quantum states of coherent light by repeatedly measuring a discrete set of field quadratures @xcite . usually , a very high detection efficiency and ad - hoc designed apparatuses with low electronic noise are required @xcite . new methods capable of discriminating between different quantum states of light , even with low detection efficiencies , will pave the road to the application of quantum homodyne detection for studying different physical systems embedded in a high noise environment @xcite .. Please generate the next two sentences of the article

for this purpose , specific quantum statistical methods , based on minimax and adaptive estimation of the wigner function , have been developed in @xcite . these approaches allow for the efficient reconstruction of the wigner function under any noise condition , at the price of acquiring larger amounts of data .

Suppose that you have an abstract for a scientific paper: a subthreshold signal is transmitted through a channel and may be detected when some noise with known structure and proportional to some level is added to the data . there is an optimal noise level , called stochastic resonance , that corresponds to the highest fisher information in the problem of estimation of the signal . as noise we consider an ergodic diffusion process and the asymptotic is considered as time goes to infinity . we propose consistent estimators of the subthreshold signal and we solve further a problem of hypotheses testing . we also discuss evidence of stochastic resonance for both estimation and hypotheses testing problems via examples . * keywords : * stochastic resonance , diffusion processes , unobservable signal detection , maximum a posterior probability . * msc : * 93e10 , 62m99 . . And you have already written the first three sentences of the full article: the term ` stochastic resonance ' was introduced in the early 80s ( see @xcite and @xcite ) in the study of periodic advance of glaciers on earth . the stochastic resonance is the effect of nonmonotone dependence of the response of a system on the noise when this noise ( for instance the temperature ) is added to a periodic input signal ( see e.g. @xcite , in which the author explains also differences and similarities with the notion of stochastic filtering ) . an extensive review on stochastic resonance and its presence in different fields of applications can be found in @xcite .. Please generate the next two sentences of the article

following @xcite , as stochastic resonance we intend the phenomenon in which the transmission of a signal can be improved ( in terms of statistical quantities ) by the addition of noise . from the statistical point of view the problem is to estimate a signal @xmath0 transmitted through a channel .

Suppose that you have an abstract for a scientific paper: the karlsruhe tritium neutrino mass experiment , katrin , aims to search for the mass of the electron neutrino with a sensitivity of @xmath0{ev / c^2}$ ] ( 90% c.l . ) and a detection limit of @xmath1{ev / c^2}$ ] ( @xmath2 ) . both a positive or a negative result will have far reaching implications for cosmology and the standard model of particle physics and will give new input for astroparticle physics and cosmology . the major components of katrin are being set up at the karlsruhe institut of technology in karlsruhe , germany , and test measurements of the individual components have started . data taking with tritium is scheduled to start in 2012 . . And you have already written the first three sentences of the full article: after neutrino oscillation experiments have shown that neutrinos possess a non - zero rest mass the question of the absolute mass scale of neutrinos has become important for particle physics and cosmology ( see e.g. @xcite ) . the goal of the karlsruhe tritium neutrino experiment ( katrin , @xcite ) is to search for the mass of the electron antineutrino with a sensitivity of @xmath0{ev / c^2}$ ] . this will probe most of the mass range in which the three neutrino flavours have nearly degenerate masses and where neutrinos are of cosmological importance . to this end a precision measurement of the endpoint region of the @xmath3-decay of tritium will be performed with katrin .. Please generate the next two sentences of the article

the shape of this spectrum depends sensitively on the neutrino mass . this will be done by using a windowless gaseous tritium source for small systematic uncertainties , and an electrostatic energy filter of mac - e filter type ( electrostatic filter with magnetic adiabatic collimation , @xcite ) for the analysis of the electron energy with high luminosity and high resolution .

Suppose that you have an abstract for a scientific paper: we give an introduction to feedback control in quantum systems , as well as an overview of the variety of applications which have been explored to date . this introductory review is aimed primarily at control theorists unfamiliar with quantum mechanics , but should also be useful to quantum physicists interested in applications of feedback control . we explain how feedback in quantum systems differs from that in traditional classical systems , and how in certain cases the results from modern optimal control theory can be applied directly to quantum systems . in addition to noise reduction and stabilization , an important application of feedback in quantum systems is adaptive measurement , and we discuss the various applications of adaptive measurements . we finish by describing specific examples of the application of feedback control to cooling and state - preparation in nano - electro - mechanical systems and single trapped atoms . . And you have already written the first three sentences of the full article: while most readers will be familiar with the notion of _ feedback control _ , for completeness we begin by defining this term . feedback control is the process of monitoring a physical system , and using this information as it is being obtained ( in real time ) to apply forces to the system so as to control its dynamics .. Please generate the next two sentences of the article

this process , which is depicted in figure [ fig1 ] , is useful if , for example , the system is subject to noise . since quantum mechanical systems , including those which are continually observed , are dynamical systems , in a broad sense the theory of feedback control developed for classical dynamical systems applies directly to quantum systems . however , there are two important caveats to this statement . the first is that most of the exact results which the theory of feedback control provides , especially those regarding the optimality and robustness of control algorithms , apply only to special subclasses of dynamical systems . in particular , most apply to linear systems driven by gaussian noise @xcite . since observed quantum systems in general obey a non - linear dynamics , an important question that arises is whether exact results regarding optimal control algorithms can be derived for special classes of quantum systems .

Suppose that you have an abstract for a scientific paper: kh 15d is a strongly variable t tauri star in the young star cluster ngc 2264 that shows a decrease in flux of 3.5 magnitudes lasting for 18 days and repeating every 48 days . the eclipsing material is likely due to orbiting dust or rocky bodies in a partial ring or warped disk that periodically occults the star . we measured the polarized spectrum in and out of eclipse at the keck and palomar observatories . outside of the eclipse , the star exhibited low polarization consistent with zero . during eclipse , the polarization increased dramatically to @xmath0% across the optical spectrum , while the spectrum had the same continuum shape as outside of eclipse and exhibited emission lines of much larger equivalent width , as previously seen . from the data , we conclude that ( a ) the scattering region is uneclipsed ; ( b ) the scattering is nearly achromatic ; ( c ) the star is likely completely eclipsed so that the flux during eclipse is entirely due to scattered light , a conclusion also argued for by the shape of the ingress and egress . we argue that the scattering is not due to electrons , but may be due to large dust grains of size @xmath1 m , similar to the interplanetary grains which scatter the zodiacal light . we construct a warped - disk model with an extended dusty atmosphere which reproduces the main features of the lightcurve , namely ( a ) a gradual decrease before ingress due to extinction in the atmosphere ( similar for egress ) ; ( b ) a sharper decrease within ingress due to the optically - thick base of the atmosphere ; ( c ) a polarized flux during eclipse which is 0.1% of the total flux outside of eclipse , which requires no fine - tuning of the model . the inclination of the warp is set by the duration of ingress and egress assuming that the warp is located at the keplerian radius , and the inclination of the observer is then determined by the duration of the eclipse . . And you have already written the first three sentences of the full article: t tauri stars are thought to be young stars that are still accreting gas through a disk . @xcite discovered t tauri star kh 15d ( k7 v , @xmath2 pc ) , which shows an eclipse for 1/3 of its period , implying that it is obscured by faint circumstellar material rather than a stellar companion ; earlier data showed the star rebrighten at mid - eclipse , although this has weakened in recent data @xcite . this indicates that the obscuring material subtends a large angle , which may herald the presence a low mass stellar companion to shepherd the material via resonant interaction or to create a distorted disk @xcite .. Please generate the next two sentences of the article

in addition , the duration of the eclipse trough is lengthening over time , changing from 16 days to 18 days over 5 years , and data from 50 - 90 years ago showed no evidence for eclipses @xcite , which means that the obscuring material is rapidly evolving . during eclipse , residual flux is still present at a level of @xmath31/20 of the flux outside of eclipse indicating that either ( a ) the obscuring material is porous ( covering factor is @xmath4 ) , ( b ) the eclipse is total , but scattered light `` fills in '' the eclipse , creating some residual flux , ( c ) some flux is scattered and some transmitted . the scattering interpretation may be favored as the star becomes slightly bluer during eclipse as one would expect from scattered light , although the fluctuations in color are comparable to the color difference @xcite . in addition , the equivalent width of h@xmath5 increases dramatically from 2 to @xmath6 indicating a change from an unobscured `` weak - line '' t tauri star to a classical t tauri star ! the eclipse provides a natural `` coronagraph '' during which the suppression of stellar light allows any scattering by surrounding material to become more prominent . we attempted to distinguish the above possibilities by carrying out spectropolarimetry inside and outside of the eclipse .